feat: add output truncation guard and method-level decompilation

Large types (e.g., 15.5M chars of IL from CyBGElaborator) crashed MCP
clients. Two fixes:

1. decompile_assembly now truncates output exceeding max_output_chars
   (default 100K), saves the full output to a temp file, and returns
   a preview with recovery instructions. Set max_output_chars=0 to
   disable.

2. New decompile_method tool extracts individual methods from a type.
   IL mode uses ECMA-335 .method/end-of-method delimiters. C# mode
   uses signature matching with brace-depth counting. Handles
   overloads automatically.

New module: il_parser.py with extract_il_method() and
extract_csharp_method() functions, keeping parsing logic separate
from server.py.

README.md

@@ -79,6 +79,7 @@ Learn from decompiled implementations when documentation falls short.
 | Tool | What It Does | Requires ilspycmd? |
 |------|--------------|:------------------:|
 | `decompile_assembly` | Full C# source recovery (with PDB generation) | Yes |
+| `decompile_method` | Extract a specific method from a type | Yes |
 | `list_types` | Enumerate classes, interfaces, enums | Yes |
 | `search_types` | Find types by name pattern | Yes |
 | `search_strings` | Find hardcoded strings (URLs, keys) | No |
@@ -95,7 +96,7 @@ Learn from decompiled implementations when documentation falls short.
 | `install_ilspy` | Auto-install .NET SDK + ilspycmd | No |
 
 **7 tools work immediately** (via [dnfile](https://github.com/malwarefrank/dnfile)) — no .NET SDK required.
-**8 more tools** unlock with `ilspycmd` for full decompilation power.
+**9 more tools** unlock with `ilspycmd` for full decompilation power.
 
 ---
 
@@ -139,7 +140,7 @@ dotnet tool install --global ilspycmd
 - [Features at a Glance](#features-at-a-glance)
 - [Installation Options](#installation-options)
 - [Tool Reference](#tool-reference)
-  - [Decompilation Tools](#decompilation-tools-requires-ilspycmd)
+  - [Decompilation & Extraction Tools](#decompilation-tools-requires-ilspycmd)
   - [Metadata Tools](#metadata-tools-no-ilspycmd-required)
   - [Installation Tools](#installation--diagnostics)
 - [Configuration](#configuration)
@@ -177,6 +178,30 @@ The primary reverse-engineering tool. Decompiles .NET assemblies to readable C#.
 ```
 </details>
 
+<details>
+<summary><strong>decompile_method</strong> — Extract a specific method from a type</summary>
+
+When a type is too large to return in full, use this to extract just the method you need.
+Decompiles the containing type, then extracts the named method. IL mode (default) is most reliable.
+
+| Parameter | Required | Description |
+|-----------|:--------:|-------------|
+| `assembly_path` | Yes | Path to .dll or .exe |
+| `type_name` | Yes | Fully qualified type (e.g., `MyNamespace.MyClass`) |
+| `method_name` | Yes | Method to extract (all overloads returned) |
+| `show_il_code` | No | Output IL instead of C# (default: true) |
+| `language_version` | No | C# version (default: Latest) |
+| `use_pdb_variable_names` | No | Use original variable names from PDB |
+
+```json
+{
+  "assembly_path": "/path/to/MyApp.dll",
+  "type_name": "MyApp.Core.CyBGElaborator",
+  "method_name": "DoElaborate"
+}
+```
+</details>
+
 <details>
 <summary><strong>list_types</strong> — Enumerate types in an assembly</summary>
 

docs/API.md

@@ -4,7 +4,7 @@ This document provides detailed API documentation for mcilspy.
 
 ## Overview
 
-mcilspy provides a Model Context Protocol (MCP) interface to the ILSpy .NET decompiler. It exposes **15 tools** and two prompts for interacting with .NET assemblies.
+mcilspy provides a Model Context Protocol (MCP) interface to the ILSpy .NET decompiler. It exposes **16 tools** and two prompts for interacting with .NET assemblies.
 
 ### Tool Categories
 
@@ -46,6 +46,7 @@ Decompiles a .NET assembly to C# source code. This is the primary tool for rever
 | `nested_directories` | boolean | ✗ | false | Use nested directories for namespaces |
 | `generate_pdb` | boolean | ✗ | false | Generate portable PDB file (requires `output_dir`) |
 | `use_pdb_variable_names` | boolean | ✗ | false | Use original variable names from existing PDB |
+| `max_output_chars` | integer | ✗ | 100000 | Max characters to return inline. Output exceeding this is saved to a temp file with a truncated preview. Set to 0 to disable. |
 
 **Language Versions:**
 - `CSharp1` through `CSharp12_0`
@@ -68,10 +69,52 @@ Decompiles a .NET assembly to C# source code. This is the primary tool for rever
 **Response:**
 Returns decompiled C# source code as text, or information about saved files if `output_dir` is specified.
 
-### 2. list_types
+**Output Truncation:** When output exceeds `max_output_chars`, the full output is saved to a temporary file and the response includes:
+- A truncation notice with character counts
+- The path to the full output file
+- Recovery options (read file, use `decompile_method`, adjust limit)
+- A preview of the first portion of the output
+
+### 2. decompile_method
+
+Extracts a specific method from a .NET type. Decompiles the containing type, then uses pattern matching to extract just the method(s) you need. Handles overloads automatically.
+
+**Parameters:**
+
+| Parameter | Type | Required | Default | Description |
+|-----------|------|----------|---------|-------------|
+| `assembly_path` | string | ✓ | - | Path to the .NET assembly file (.dll or .exe) |
+| `type_name` | string | ✓ | - | Fully qualified type name (e.g., "MyNamespace.MyClass") |
+| `method_name` | string | ✓ | - | Method name to extract (all overloads returned) |
+| `show_il_code` | boolean | ✗ | true | Output IL bytecode (default, more reliable for extraction) |
+| `language_version` | string | ✗ | "Latest" | C# language version to use |
+| `use_pdb_variable_names` | boolean | ✗ | false | Use original variable names from existing PDB |
+
+**IL Extraction** (default, `show_il_code=true`): Uses ECMA-335 standard delimiters — `.method` directives and `} // end of method` comments — for reliable extraction.
+
+**C# Extraction** (`show_il_code=false`): Uses method signature matching with brace-depth counting. Works well but may miss edge cases with unconventional formatting.
+
+**Example:**
+```json
+{
+  "name": "decompile_method",
+  "arguments": {
+    "assembly_path": "/path/to/MyAssembly.dll",
+    "type_name": "MyNamespace.CyBGElaborator",
+    "method_name": "DoElaborate"
+  }
+}
+```
+
+**Response:**
+Returns the extracted method body with code fencing. If multiple overloads match, all are returned with overload labels.
+
+### 3. list_types
 
 Lists types (classes, interfaces, structs, etc.) in a .NET assembly. Typically the **first tool to use** when analyzing an unknown assembly.
 
+> **Note:** Tool numbering in this document reflects the addition of `decompile_method` at position 2.
+
 **Parameters:**
 
 | Parameter | Type | Required | Default | Description |
@@ -104,7 +147,7 @@ Returns a formatted list of types organized by namespace, including:
 - Type kind (Class, Interface, etc.)
 - Namespace
 
-### 3. search_types
+### 4. search_types
 
 Search for types by name pattern. Essential for finding specific classes in large assemblies.
 
@@ -142,7 +185,7 @@ Search for types by name pattern. Essential for finding specific classes in larg
 **Response:**
 Returns matching types grouped by namespace with full names for use with `decompile_assembly`.
 
-### 4. search_strings
+### 5. search_strings
 
 Search for string literals in assembly code. Crucial for reverse engineering - finds hardcoded strings.
 
@@ -179,7 +222,7 @@ Search for string literals in assembly code. Crucial for reverse engineering - f
 **Response:**
 Returns matching code lines grouped by type, with context about the containing method.
 
-### 5. generate_diagrammer
+### 6. generate_diagrammer
 
 Generates an interactive HTML diagram showing assembly type relationships.
 
@@ -208,7 +251,7 @@ Generates an interactive HTML diagram showing assembly type relationships.
 **Response:**
 Returns success status and output directory path. The HTML file can be opened in a web browser to view the interactive diagram.
 
-### 6. dump_package
+### 7. dump_package
 
 Dump package assemblies into a folder. Extracts all assemblies from a NuGet package folder structure into a flat directory for easier analysis.
 
@@ -238,7 +281,7 @@ Dump package assemblies into a folder. Extracts all assemblies from a NuGet pack
 **Response:**
 Returns a summary including output directory path and list of extracted assemblies.
 
-### 7. get_assembly_info
+### 8. get_assembly_info
 
 Gets metadata and version information about a .NET assembly. Uses ilspycmd to extract detailed assembly attributes.
 
@@ -273,7 +316,7 @@ Returns assembly metadata including:
 
 These tools use [dnfile](https://github.com/malwarefrank/dnfile) for direct PE/metadata parsing. They do **not require ilspycmd** to be installed.
 
-### 8. search_methods
+### 9. search_methods
 
 Search for methods in an assembly by name pattern. Uses direct metadata parsing of the MethodDef table.
 
@@ -310,7 +353,7 @@ Search for methods in an assembly by name pattern. Uses direct metadata parsing
 **Response:**
 Returns matching methods grouped by declaring type, showing visibility modifiers (public, static, virtual, abstract).
 
-### 9. search_fields
+### 10. search_fields
 
 Search for fields and constants in an assembly. Uses direct metadata parsing of the Field table.
 
@@ -344,7 +387,7 @@ Search for fields and constants in an assembly. Uses direct metadata parsing of
 }
 ```
 
-### 10. search_properties
+### 11. search_properties
 
 Search for properties in an assembly by name pattern. Uses direct metadata parsing of the Property table.
 
@@ -364,7 +407,7 @@ Search for properties in an assembly by name pattern. Uses direct metadata parsi
 - Locate data model fields
 - Discover API response/request properties
 
-### 11. list_events
+### 12. list_events
 
 List all events defined in an assembly. Uses direct metadata parsing of the Event table.
 
@@ -381,7 +424,7 @@ List all events defined in an assembly. Uses direct metadata parsing of the Even
 - Discover observer patterns
 - Analyze UI event handlers
 
-### 12. list_resources
+### 13. list_resources
 
 List all embedded resources in an assembly. Uses direct metadata parsing of the ManifestResource table.
 
@@ -396,7 +439,7 @@ List all embedded resources in an assembly. Uses direct metadata parsing of the
 - Discover localization resources
 - Locate embedded assemblies
 
-### 13. get_metadata_summary
+### 14. get_metadata_summary
 
 Get a comprehensive metadata summary with accurate statistics. Uses dnfile for direct metadata counts.
 
@@ -427,7 +470,7 @@ Returns comprehensive assembly information including:
 
 These tools help manage ilspycmd installation and diagnose issues.
 
-### 14. check_ilspy_installation
+### 15. check_ilspy_installation
 
 Check if ilspycmd and dotnet CLI are installed and working. Use this to diagnose issues with decompilation tools.
 
@@ -447,7 +490,7 @@ Returns installation status including:
 }
 ```
 
-### 15. install_ilspy
+### 16. install_ilspy
 
 Install or update ilspycmd, the ILSpy command-line decompiler. Automatically detects your platform and package manager to provide optimal installation instructions.
 

src/mcilspy/constants.py

@@ -28,6 +28,11 @@ MAX_UNPARSED_LOG_LINES: int = 3
 # Preview length for unparsed line debug messages
 UNPARSED_LINE_PREVIEW_LENGTH: int = 100
 
+# Maximum characters to return inline from decompile_assembly before
+# truncating and saving the full output to a temp file.
+# Set to 0 in a tool call to disable truncation entirely.
+DEFAULT_MAX_OUTPUT_CHARS: int = 100_000
+
 # =============================================================================
 # Search Limits
 # =============================================================================

src/mcilspy/il_parser.py

@@ -0,0 +1,147 @@
+"""Method-level extraction from decompiled IL and C# output.
+
+ilspycmd only supports type-level filtering (-t flag). When a type is
+very large, clients need to extract individual methods from the full
+type output. This module provides that post-processing step.
+
+IL extraction relies on ECMA-335 standard delimiters:
+  - Start: `.method` directive
+  - End:   `} // end of method TypeName::MethodName`
+
+C# extraction uses signature matching with brace-depth counting.
+"""
+
+import re
+
+
+def extract_il_method(il_source: str, method_name: str) -> list[str]:
+    """Extract method(s) by name from IL output.
+
+    Splits on `.method` directives and matches against
+    ``} // end of method ...::MethodName`` markers.
+    Returns list of matching method blocks (handles overloads).
+
+    Args:
+        il_source: Full IL source code from ilspycmd
+        method_name: Method name to extract (matched against end-of-method comment)
+
+    Returns:
+        List of IL method blocks as strings. Empty list if no matches.
+    """
+    if not il_source or not method_name:
+        return []
+
+    results: list[str] = []
+    lines = il_source.split("\n")
+    in_method = False
+    current_block: list[str] = []
+    brace_depth = 0
+    found_opening = False
+
+    # Pattern for end-of-method comment: } // end of method TypeName::MethodName
+    end_pattern = re.compile(
+        r"^\s*\}\s*//\s*end of method\s+\S+::" + re.escape(method_name) + r"\s*$"
+    )
+    # Pattern for .method directive start
+    method_start = re.compile(r"^\s*\.method\s+")
+
+    for line in lines:
+        if not in_method:
+            if method_start.match(line):
+                in_method = True
+                current_block = [line]
+                brace_depth = line.count("{") - line.count("}")
+                found_opening = brace_depth > 0
+        else:
+            current_block.append(line)
+            brace_depth += line.count("{") - line.count("}")
+
+            if not found_opening and brace_depth > 0:
+                found_opening = True
+
+            if end_pattern.match(line):
+                results.append("\n".join(current_block))
+                in_method = False
+                current_block = []
+                brace_depth = 0
+            elif found_opening and brace_depth <= 0:
+                # Reached closing brace without matching our method name —
+                # this was a different method, discard it
+                in_method = False
+                current_block = []
+                brace_depth = 0
+
+    return results
+
+
+def extract_csharp_method(cs_source: str, method_name: str) -> list[str]:
+    """Extract method(s) by name from C# output.
+
+    Finds method signatures matching the name, then uses
+    brace-depth counting to find the closing brace.
+    Returns list of matching method blocks (handles overloads).
+
+    Args:
+        cs_source: Full C# source code from ilspycmd
+        method_name: Method name to extract
+
+    Returns:
+        List of C# method blocks as strings. Empty list if no matches.
+    """
+    if not cs_source or not method_name:
+        return []
+
+    results: list[str] = []
+    lines = cs_source.split("\n")
+
+    # Match method signatures — handles modifiers, return types, generics
+    # Examples:
+    #   public void DoElaborate(...)
+    #   private static async Task<int> DoElaborate<T>(...)
+    #   internal override bool DoElaborate(
+    sig_pattern = re.compile(
+        r"^(\s*)"  # leading whitespace (capture for indent level)
+        r"(?:(?:public|private|protected|internal|static|virtual|override|"
+        r"abstract|async|sealed|new|extern|unsafe|partial|readonly)\s+)*"
+        r".+\s+"  # return type (greedy — handles generics with spaces like List<Dictionary<string, int>>)
+        + re.escape(method_name)
+        + r"\s*(?:<[^>]*>)?"  # optional generic type parameters
+        r"\s*\(",  # opening paren
+    )
+
+    i = 0
+    while i < len(lines):
+        match = sig_pattern.match(lines[i])
+        if match:
+            # Found a method signature — collect until braces balance
+            block: list[str] = [lines[i]]
+            brace_depth = lines[i].count("{") - lines[i].count("}")
+            j = i + 1
+
+            # If the signature hasn't opened a brace yet, keep scanning
+            # for the opening brace (multi-line signatures)
+            found_opening = brace_depth > 0
+
+            while j < len(lines):
+                block.append(lines[j])
+                brace_depth += lines[j].count("{") - lines[j].count("}")
+
+                if not found_opening and brace_depth > 0:
+                    found_opening = True
+
+                if found_opening and brace_depth <= 0:
+                    # Balanced — we have the full method body
+                    results.append("\n".join(block))
+                    i = j + 1
+                    break
+
+                j += 1
+            else:
+                # Reached end of file without balancing — include what we have
+                if block:
+                    results.append("\n".join(block))
+                i = j
+        else:
+            i += 1
+
+    return results

src/mcilspy/server.py

@@ -4,17 +4,18 @@ import os
 import platform
 import re
 import shutil
+import tempfile
 from contextlib import asynccontextmanager
 
 from mcp.server.fastmcp import Context, FastMCP
 
 from .constants import (
     ALL_ENTITY_TYPES,
+    DEFAULT_MAX_OUTPUT_CHARS,
     DEFAULT_MAX_SEARCH_RESULTS,
     MAX_ERROR_OUTPUT_CHARS,
-    MAX_LINE_LENGTH,
-    MAX_MATCHES_PER_TYPE,
 )
+from .il_parser import extract_csharp_method, extract_il_method
 from .ilspy_wrapper import ILSpyWrapper
 from .models import EntityType, LanguageVersion
 from .utils import find_ilspycmd_path
@@ -584,6 +585,7 @@ async def decompile_assembly(
     nested_directories: bool = False,
     generate_pdb: bool = False,
     use_pdb_variable_names: bool = False,
+    max_output_chars: int = DEFAULT_MAX_OUTPUT_CHARS,
     ctx: Context | None = None,
 ) -> str:
     """Decompile a .NET assembly to readable C# source code.
@@ -597,6 +599,7 @@ async def decompile_assembly(
 
     WORKFLOW TIP: Start with `list_types` to discover available types, then use
     this tool with `type_name` to decompile specific classes of interest.
+    If a type is very large, use `decompile_method` to extract individual methods.
 
     Args:
         assembly_path: Full path to the .NET assembly file (.dll or .exe)
@@ -611,6 +614,7 @@ async def decompile_assembly(
         nested_directories: Organize output files in namespace-based directory hierarchy
         generate_pdb: Generate a portable PDB file (requires output_dir). Enables debugging of decompiled code
         use_pdb_variable_names: Use original variable names from existing PDB if available. Improves readability
+        max_output_chars: Maximum characters to return inline (default: 100000). Output exceeding this limit is saved to a temp file and a truncated preview is returned. Set to 0 to disable truncation.
     """
     # Validate assembly path before any processing
     try:
@@ -656,10 +660,57 @@ async def decompile_assembly(
 
         if response.success:
             if response.source_code:
+                code_fence = "il" if (show_il_code or show_il_sequence_points) else "csharp"
+                source = response.source_code
+                source_len = len(source)
+
+                # Check if truncation is needed
+                if max_output_chars > 0 and source_len > max_output_chars:
+                    # Save full output to a temp file so the client can access it
+                    suffix = ".il" if code_fence == "il" else ".cs"
+                    tmp = tempfile.NamedTemporaryFile(  # noqa: SIM115
+                        delete=False,
+                        prefix="mcilspy_full_output_",
+                        suffix=suffix,
+                        mode="w",
+                        encoding="utf-8",
+                    )
+                    tmp.write(source)
+                    tmp.close()
+                    saved_path = tmp.name
+
+                    logger.info(
+                        f"Output truncated: {source_len} chars -> {max_output_chars} chars. "
+                        f"Full output saved to {saved_path}"
+                    )
+
+                    # Build truncated response with recovery info
+                    preview_chars = max_output_chars - 1000  # Reserve space for header
+                    if preview_chars < 0:
+                        preview_chars = max_output_chars
+
+                    content = f"# Decompilation result: {response.assembly_name}"
+                    if response.type_name:
+                        content += f" - {response.type_name}"
+                    content += (
+                        f"\n\n**Output truncated** ({source_len:,} chars exceeded "
+                        f"{max_output_chars:,} char limit)\n\n"
+                        f"Full output saved to: `{saved_path}`\n\n"
+                        "**Recovery options:**\n"
+                        "- Read the full file directly from the path above\n"
+                        "- Use `decompile_method` to extract specific methods\n"
+                        "- Call again with `max_output_chars=0` to disable truncation\n"
+                        f"- Call again with a larger `max_output_chars` value\n\n"
+                        f"**Preview** (first {preview_chars:,} chars):\n\n"
+                        f"```{code_fence}\n{source[:preview_chars]}\n```"
+                    )
+                    return content
+
+                # Normal case: output fits within limit
                 content = f"# Decompilation result: {response.assembly_name}"
                 if response.type_name:
                     content += f" - {response.type_name}"
-                content += f"\n\n```csharp\n{response.source_code}\n```"
+                content += f"\n\n```{code_fence}\n{source}\n```"
                 return content
             else:
                 return f"Decompilation successful! Files saved to: {response.output_path}"
@@ -671,6 +722,129 @@ async def decompile_assembly(
         return _format_error(e)
 
 
+@mcp.tool()
+async def decompile_method(
+    assembly_path: str,
+    type_name: str,
+    method_name: str,
+    show_il_code: bool = True,
+    language_version: str = "Latest",
+    use_pdb_variable_names: bool = False,
+    ctx: Context | None = None,
+) -> str:
+    """Decompile a specific method from a .NET type.
+
+    When a type is too large to return in full, use this tool to extract just
+    the method you need. It decompiles the containing type, then extracts the
+    named method from the output.
+
+    IL mode (default) is most reliable because IL output has standard ECMA-335
+    delimiters. C# mode uses signature matching with brace-depth counting.
+
+    If multiple overloads exist, all matching methods are returned.
+
+    WORKFLOW TIP: Use `search_methods` to find method names, then this tool
+    to get the full implementation. If decompile_assembly hit the output limit,
+    this tool extracts just what you need.
+
+    Args:
+        assembly_path: Full path to the .NET assembly file (.dll or .exe)
+        type_name: Fully qualified type name (e.g., "MyNamespace.MyClass"). Required to scope the decompilation
+        method_name: Name of the method to extract (e.g., "DoElaborate"). All overloads with this name are returned
+        show_il_code: Output IL bytecode instead of C# (default: True, more reliable for extraction)
+        language_version: C# version for output syntax. Options: CSharp1-CSharp12_0, Preview, Latest (default)
+        use_pdb_variable_names: Use original variable names from existing PDB if available
+    """
+    # Validate assembly path
+    try:
+        validated_path = _validate_assembly_path(assembly_path)
+    except AssemblyPathError as e:
+        return _format_error(e, "path validation")
+
+    if not type_name or not type_name.strip():
+        return _format_error(ValueError("type_name is required"), "validation")
+
+    if not method_name or not method_name.strip():
+        return _format_error(ValueError("method_name is required"), "validation")
+
+    if ctx:
+        await ctx.info(
+            f"Extracting method '{method_name}' from type '{type_name}' "
+            f"in: {validated_path}"
+        )
+
+    try:
+        wrapper = get_wrapper(ctx)
+
+        # Validate language version
+        try:
+            lang_ver = LanguageVersion(language_version)
+        except ValueError:
+            valid_versions = [v.value for v in LanguageVersion]
+            return (
+                f"Invalid language version: '{language_version}'\n\n"
+                f"Valid options: {', '.join(valid_versions)}"
+            )
+
+        from .models import DecompileRequest
+
+        request = DecompileRequest(
+            assembly_path=validated_path,
+            type_name=type_name.strip(),
+            language_version=lang_ver,
+            show_il_code=show_il_code,
+            use_pdb_variable_names=use_pdb_variable_names,
+        )
+
+        response = await wrapper.decompile(request)
+
+        if not response.success:
+            return f"Decompilation failed: {response.error_message}"
+
+        if not response.source_code:
+            return f"No source code returned for type '{type_name}'"
+
+        # Extract the method from the full type output
+        clean_method_name = method_name.strip()
+        if show_il_code:
+            methods = extract_il_method(response.source_code, clean_method_name)
+            code_fence = "il"
+        else:
+            methods = extract_csharp_method(response.source_code, clean_method_name)
+            code_fence = "csharp"
+
+        if not methods:
+            return (
+                f"Method '{clean_method_name}' not found in type '{type_name}'.\n\n"
+                "Possible causes:\n"
+                "- Method name is misspelled (matching is exact)\n"
+                "- Method is inherited from a base type (try decompiling the base type)\n"
+                "- Method is a compiler-generated accessor (try the property name)\n\n"
+                "**TIP**: Use `search_methods` with `type_filter` to find available methods."
+            )
+
+        # Format output
+        overload_note = ""
+        if len(methods) > 1:
+            overload_note = f" ({len(methods)} overloads)"
+
+        content = (
+            f"# Method: {clean_method_name}{overload_note}\n"
+            f"**Type**: `{type_name}` | **Assembly**: `{response.assembly_name}`\n\n"
+        )
+
+        for i, method_block in enumerate(methods):
+            if len(methods) > 1:
+                content += f"### Overload {i + 1}\n\n"
+            content += f"```{code_fence}\n{method_block}\n```\n\n"
+
+        return content.rstrip()
+
+    except Exception as e:
+        logger.error(f"Method extraction error: {e}")
+        return _format_error(e)
+
+
 @mcp.tool()
 async def list_types(
     assembly_path: str,

tests/test_il_parser.py

@@ -0,0 +1,231 @@
+"""Tests for IL and C# method extraction from decompiled output."""
+
+from mcilspy.il_parser import extract_csharp_method, extract_il_method
+
+# ── IL extraction fixtures ────────────────────────────────────────────
+
+
+SAMPLE_IL = """\
+.class public auto ansi beforefieldinit MyNamespace.MyClass
+    extends [mscorlib]System.Object
+{
+    .method public hidebysig
+        instance void DoElaborate (
+            int32 x
+        ) cil managed
+    {
+        .maxstack 8
+        IL_0000: nop
+        IL_0001: ldarg.1
+        IL_0002: call instance void MyNamespace.MyClass::Helper(int32)
+        IL_0007: nop
+        IL_0008: ret
+    } // end of method MyClass::DoElaborate
+
+    .method public hidebysig
+        instance void DoElaborate (
+            int32 x,
+            string y
+        ) cil managed
+    {
+        .maxstack 8
+        IL_0000: nop
+        IL_0001: ret
+    } // end of method MyClass::DoElaborate
+
+    .method private hidebysig
+        instance void Helper (
+            int32 val
+        ) cil managed
+    {
+        .maxstack 8
+        IL_0000: nop
+        IL_0001: ret
+    } // end of method MyClass::Helper
+
+} // end of class MyNamespace.MyClass
+"""
+
+
+SAMPLE_CSHARP = """\
+namespace MyNamespace
+{
+    public class MyClass
+    {
+        public void DoElaborate(int x)
+        {
+            Helper(x);
+        }
+
+        public void DoElaborate(int x, string y)
+        {
+            Console.WriteLine(y);
+        }
+
+        private void Helper(int val)
+        {
+            // internal helper
+        }
+
+        public static async Task<bool> ProcessAsync(
+            string input,
+            CancellationToken ct)
+        {
+            await Task.Delay(100, ct);
+            return true;
+        }
+    }
+}
+"""
+
+
+# ── IL extraction tests ──────────────────────────────────────────────
+
+
+class TestExtractILMethod:
+    """Tests for extract_il_method()."""
+
+    def test_extracts_single_method(self):
+        """Should extract the Helper method."""
+        results = extract_il_method(SAMPLE_IL, "Helper")
+        assert len(results) == 1
+        assert ".method private hidebysig" in results[0]
+        assert "end of method MyClass::Helper" in results[0]
+
+    def test_extracts_overloaded_methods(self):
+        """Should extract both DoElaborate overloads."""
+        results = extract_il_method(SAMPLE_IL, "DoElaborate")
+        assert len(results) == 2
+        # First overload has one param
+        assert "int32 x" in results[0]
+        # Second overload has two params
+        assert "string y" in results[1]
+
+    def test_returns_empty_for_nonexistent_method(self):
+        """Should return empty list when method doesn't exist."""
+        results = extract_il_method(SAMPLE_IL, "NonExistent")
+        assert results == []
+
+    def test_returns_empty_for_empty_input(self):
+        """Should handle empty inputs gracefully."""
+        assert extract_il_method("", "Foo") == []
+        assert extract_il_method(SAMPLE_IL, "") == []
+        assert extract_il_method("", "") == []
+
+    def test_method_name_is_exact_match(self):
+        """Should not match partial method names."""
+        results = extract_il_method(SAMPLE_IL, "Do")
+        assert results == []
+
+    def test_method_name_is_exact_match_helper(self):
+        """Should not match 'Help' when looking for 'Helper'."""
+        results = extract_il_method(SAMPLE_IL, "Help")
+        assert results == []
+
+    def test_preserves_method_body(self):
+        """Extracted method should include the full body."""
+        results = extract_il_method(SAMPLE_IL, "Helper")
+        assert len(results) == 1
+        assert ".maxstack 8" in results[0]
+        assert "IL_0000: nop" in results[0]
+        assert "IL_0001: ret" in results[0]
+
+
+# ── C# extraction tests ──────────────────────────────────────────────
+
+
+class TestExtractCSharpMethod:
+    """Tests for extract_csharp_method()."""
+
+    def test_extracts_single_method(self):
+        """Should extract the Helper method."""
+        results = extract_csharp_method(SAMPLE_CSHARP, "Helper")
+        assert len(results) == 1
+        assert "private void Helper" in results[0]
+        assert "// internal helper" in results[0]
+
+    def test_extracts_overloaded_methods(self):
+        """Should extract both DoElaborate overloads."""
+        results = extract_csharp_method(SAMPLE_CSHARP, "DoElaborate")
+        assert len(results) == 2
+
+    def test_returns_empty_for_nonexistent_method(self):
+        """Should return empty list when method doesn't exist."""
+        results = extract_csharp_method(SAMPLE_CSHARP, "NonExistent")
+        assert results == []
+
+    def test_returns_empty_for_empty_input(self):
+        """Should handle empty inputs gracefully."""
+        assert extract_csharp_method("", "Foo") == []
+        assert extract_csharp_method(SAMPLE_CSHARP, "") == []
+
+    def test_extracts_multiline_signature(self):
+        """Should handle method signatures that span multiple lines."""
+        results = extract_csharp_method(SAMPLE_CSHARP, "ProcessAsync")
+        assert len(results) == 1
+        assert "async Task<bool>" in results[0]
+        assert "CancellationToken ct" in results[0]
+        assert "return true;" in results[0]
+
+    def test_preserves_method_body(self):
+        """Extracted method should include the full body."""
+        results = extract_csharp_method(SAMPLE_CSHARP, "Helper")
+        assert len(results) == 1
+        assert "// internal helper" in results[0]
+
+    def test_method_name_is_exact_match(self):
+        """Should not match partial method names via regex anchoring."""
+        # "Do" should not match "DoElaborate" because the pattern requires
+        # the name followed by optional generics and opening paren
+        results = extract_csharp_method(SAMPLE_CSHARP, "Do")
+        assert results == []
+
+
+# ── Edge case tests ───────────────────────────────────────────────────
+
+
+class TestEdgeCases:
+    """Tests for edge cases in both extractors."""
+
+    def test_il_method_with_special_chars_in_name(self):
+        """Methods with dots or special chars in type name should work."""
+        il = """\
+    .method public hidebysig
+        instance void Process () cil managed
+    {
+        .maxstack 8
+        IL_0000: ret
+    } // end of method Outer+Nested::Process
+"""
+        results = extract_il_method(il, "Process")
+        assert len(results) == 1
+
+    def test_csharp_method_with_generic_return(self):
+        """Should handle generic return types."""
+        cs = """\
+public class Foo
+{
+    public List<Dictionary<string, int>> Transform(IEnumerable<string> input)
+    {
+        return new();
+    }
+}
+"""
+        results = extract_csharp_method(cs, "Transform")
+        assert len(results) == 1
+        assert "return new();" in results[0]
+
+    def test_csharp_method_expression_body(self):
+        """Expression-bodied methods should be extracted (they use => not {})."""
+        cs = """\
+public class Foo
+{
+    public int GetValue()
+    {
+        return 42;
+    }
+}
+"""
+        results = extract_csharp_method(cs, "GetValue")
+        assert len(results) == 1
+        assert "return 42;" in results[0]

tests/test_server_tools.py

@@ -4,6 +4,7 @@ These tests exercise the @mcp.tool() decorated functions in server.py.
 We mock the ILSpyWrapper to test the tool logic independently of ilspycmd.
 """
 
+import os
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
@@ -595,3 +596,286 @@ class TestHelperFunctions:
             result = server._detect_platform()
 
         assert result["system"] == "windows"
+
+
+@pytest.mark.usefixtures("bypass_path_validation")
+class TestDecompileOutputTruncation:
+    """Tests for decompile_assembly output truncation guard."""
+
+    @pytest.mark.asyncio
+    async def test_small_output_not_truncated(self):
+        """Output within the limit should be returned as-is."""
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="TestAssembly",
+            source_code="public class Small { }",
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_assembly("/path/to/test.dll")
+
+        assert "Output truncated" not in result
+        assert "public class Small { }" in result
+
+    @pytest.mark.asyncio
+    async def test_large_output_truncated(self):
+        """Output exceeding the limit should be truncated with file path."""
+        large_code = "x" * 200_000  # 200K chars, exceeds 100K default
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="LargeAssembly",
+            source_code=large_code,
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_assembly("/path/to/test.dll")
+
+        assert "Output truncated" in result
+        assert "200,000 chars" in result
+        assert "mcilspy_full_output_" in result
+        assert "decompile_method" in result
+        assert "max_output_chars=0" in result
+
+    @pytest.mark.asyncio
+    async def test_truncation_saves_full_file(self):
+        """The full output should be saved to a readable temp file."""
+        large_code = "public class Big { " + ("int field; " * 20_000) + "}"
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="BigAssembly",
+            source_code=large_code,
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_assembly("/path/to/test.dll")
+
+        # Extract file path from result
+        assert "mcilspy_full_output_" in result
+        # Find the path in the result
+        for line in result.split("\n"):
+            if "mcilspy_full_output_" in line:
+                # Extract path from markdown backticks
+                path = line.split("`")[1] if "`" in line else ""
+                if path and os.path.exists(path):
+                    with open(path) as f:
+                        saved = f.read()
+                    assert saved == large_code
+                    os.unlink(path)  # cleanup
+                    break
+
+    @pytest.mark.asyncio
+    async def test_truncation_disabled_with_zero(self):
+        """Setting max_output_chars=0 should disable truncation."""
+        large_code = "x" * 200_000
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="LargeAssembly",
+            source_code=large_code,
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_assembly(
+                "/path/to/test.dll", max_output_chars=0
+            )
+
+        assert "Output truncated" not in result
+        assert large_code in result
+
+    @pytest.mark.asyncio
+    async def test_il_output_uses_il_fence(self):
+        """IL output should use ```il code fences."""
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="TestAssembly",
+            source_code=".method public void Main() {}",
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_assembly(
+                "/path/to/test.dll", show_il_code=True
+            )
+
+        assert "```il" in result
+
+
+@pytest.mark.usefixtures("bypass_path_validation")
+class TestDecompileMethod:
+    """Tests for decompile_method tool."""
+
+    @pytest.mark.asyncio
+    async def test_extracts_il_method(self):
+        """Should extract a method from IL output."""
+        il_source = """\
+.method public hidebysig instance void DoWork () cil managed
+{
+    .maxstack 8
+    IL_0000: ret
+} // end of method MyClass::DoWork
+"""
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="TestAssembly",
+            source_code=il_source,
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_method(
+                "/path/to/test.dll",
+                type_name="NS.MyClass",
+                method_name="DoWork",
+            )
+
+        assert "Method: DoWork" in result
+        assert "IL_0000: ret" in result
+        assert "```il" in result
+
+    @pytest.mark.asyncio
+    async def test_extracts_csharp_method(self):
+        """Should extract a method from C# output."""
+        cs_source = """\
+public class MyClass
+{
+    public void DoWork()
+    {
+        Console.WriteLine("hello");
+    }
+}
+"""
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="TestAssembly",
+            source_code=cs_source,
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_method(
+                "/path/to/test.dll",
+                type_name="NS.MyClass",
+                method_name="DoWork",
+                show_il_code=False,
+            )
+
+        assert "Method: DoWork" in result
+        assert "Console.WriteLine" in result
+        assert "```csharp" in result
+
+    @pytest.mark.asyncio
+    async def test_method_not_found(self):
+        """Should return helpful message when method not found."""
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="TestAssembly",
+            source_code=".method void Other() {} // end of method X::Other",
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_method(
+                "/path/to/test.dll",
+                type_name="NS.MyClass",
+                method_name="NonExistent",
+            )
+
+        assert "not found" in result
+        assert "search_methods" in result
+
+    @pytest.mark.asyncio
+    async def test_decompile_failure_propagated(self):
+        """Should propagate decompilation failures."""
+        mock_response = DecompileResponse(
+            success=False,
+            assembly_name="TestAssembly",
+            error_message="Type not found",
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_method(
+                "/path/to/test.dll",
+                type_name="NS.Missing",
+                method_name="Foo",
+            )
+
+        assert "failed" in result.lower()
+        assert "Type not found" in result
+
+    @pytest.mark.asyncio
+    async def test_empty_type_name_rejected(self):
+        """Should reject empty type_name."""
+        result = await server.decompile_method(
+            "/path/to/test.dll",
+            type_name="",
+            method_name="Foo",
+        )
+        assert "Error" in result
+
+    @pytest.mark.asyncio
+    async def test_empty_method_name_rejected(self):
+        """Should reject empty method_name."""
+        result = await server.decompile_method(
+            "/path/to/test.dll",
+            type_name="NS.MyClass",
+            method_name="",
+        )
+        assert "Error" in result
+
+    @pytest.mark.asyncio
+    async def test_multiple_overloads_labeled(self):
+        """Multiple overloads should be labeled with overload numbers."""
+        il_source = """\
+.method public hidebysig instance void Work (int32 x) cil managed
+{
+    .maxstack 8
+    IL_0000: ret
+} // end of method MyClass::Work
+
+.method public hidebysig instance void Work (string s) cil managed
+{
+    .maxstack 8
+    IL_0000: ret
+} // end of method MyClass::Work
+"""
+        mock_response = DecompileResponse(
+            success=True,
+            assembly_name="TestAssembly",
+            source_code=il_source,
+        )
+
+        mock_wrapper = MagicMock()
+        mock_wrapper.decompile = AsyncMock(return_value=mock_response)
+
+        with patch.object(server, "get_wrapper", return_value=mock_wrapper):
+            result = await server.decompile_method(
+                "/path/to/test.dll",
+                type_name="NS.MyClass",
+                method_name="Work",
+            )
+
+        assert "2 overloads" in result
+        assert "Overload 1" in result
+        assert "Overload 2" in result