diff --git a/src/ghydramcp/mixins/docker.py b/src/ghydramcp/mixins/docker.py
index f81e31b..aed393f 100644
--- a/src/ghydramcp/mixins/docker.py
+++ b/src/ghydramcp/mixins/docker.py
@@ -881,17 +881,18 @@ class DockerMixin(MCPMixin):
         description="Check if a GhydraMCP container's API is responding",
     )
     async def docker_health(
-        self, port: int = 8192, timeout: float = 5.0, ctx: Optional[Context] = None
+        self, port: Optional[int] = None, timeout: float = 5.0, ctx: Optional[Context] = None
     ) -> Dict[str, Any]:
         """Check if a GhydraMCP container's API is healthy.
 
         Args:
-            port: API port to check (default: 8192)
+            port: API port to check (uses current instance if not specified)
             timeout: Request timeout in seconds
 
         Returns:
             Health status and API info if available
         """
+        port = self.get_instance_port(port)
         loop = asyncio.get_event_loop()
         return await loop.run_in_executor(
             None, self._sync_health_check, port, timeout
@@ -982,7 +983,7 @@ class DockerMixin(MCPMixin):
             "container_name": start_result.get("name"),
             "port": actual_port,
             "api_url": f"http://localhost:{actual_port}/",
-            "message": f"Container starting on port {actual_port}. Poll docker_health(port={actual_port}) to check when ready.",
+            "message": f"Container starting on port {actual_port}. Poll docker_health(port={actual_port}), then call instances_use(port={actual_port}) when healthy.",
         }
 
     @mcp_tool(