fix: add MCP tools cache reset endpoint (#3602)

* fix: add MCP tools cache reset endpoint

* docs: clarify MCP cache reset scope

backend/app/gateway/routers/mcp.py

@@ -8,6 +8,7 @@ from fastapi import APIRouter, HTTPException, Request, status
 from pydantic import BaseModel, Field
 
 from deerflow.config.extensions_config import ExtensionsConfig, get_extensions_config, reload_extensions_config
+from deerflow.mcp.cache import reset_mcp_tools_cache
 
 logger = logging.getLogger(__name__)
 router = APIRouter(prefix="/api", tags=["mcp"])
@@ -69,6 +70,13 @@ class McpConfigUpdateRequest(BaseModel):
     )
 
 
+class McpCacheResetResponse(BaseModel):
+    """Response model for resetting the MCP tools cache."""
+
+    success: bool = Field(description="Whether the MCP tools cache was reset")
+    message: str = Field(description="Human-readable reset status")
+
+
 _MASKED_VALUE = "***"
 
 
@@ -269,6 +277,27 @@ async def get_mcp_configuration(request: Request) -> McpConfigResponse:
     return McpConfigResponse(mcp_servers=servers)
 
 
+@router.post(
+    "/mcp/cache/reset",
+    response_model=McpCacheResetResponse,
+    summary="Reset MCP Tools Cache",
+    description=("Reset cached MCP tools and pooled sessions process-wide so tools are reloaded on next use. This affects all threads and users in the current Gateway process."),
+)
+async def reset_mcp_tools_cache_endpoint(request: Request) -> McpCacheResetResponse:
+    """Reset cached MCP tools and persistent sessions process-wide.
+
+    The next agent run or tool lookup will reload tools from the configured MCP
+    servers. This affects all threads and users in the current Gateway process,
+    and avoids relying on extensions_config.json mtime changes.
+    """
+    await _require_admin_user(request)
+    reset_mcp_tools_cache()
+    return McpCacheResetResponse(
+        success=True,
+        message="MCP tools cache reset. Tools will reload on next use.",
+    )
+
+
 @router.put(
     "/mcp/config",
     response_model=McpConfigResponse,
@@ -363,6 +392,7 @@ async def update_mcp_configuration(request: Request, body: McpConfigUpdateReques
         # agent runtime lives in Gateway, so this keeps API reads and tool
         # execution aligned after extensions_config.json changes.
         reloaded_config = reload_extensions_config()
+        reset_mcp_tools_cache()
         servers = {name: _mask_server_config(McpServerConfigResponse(**server.model_dump())) for name, server in reloaded_config.mcp_servers.items()}
         return McpConfigResponse(mcp_servers=servers)