BerriAI/litellm · error · HTTPException

Parameters {disallowed_params} are not allowed for tool {too

Error message

Parameters {disallowed_params} are not allowed for tool {tool_name}. Allowed parameters: {allowed_params_list}. Contact proxy admin to allow these parameters.

What it means

Argument-filter guard: allowed_params is configured for the tool and the call supplied keys outside the allowlist. The call is rejected with the permitted list because silently dropping admin-restricted parameters would change tool semantics.

Source

Thrown at litellm/proxy/_experimental/mcp_server/mcp_server_manager.py:4489

        Returns:
            Filtered dictionary containing only allowed parameters

        Raises:
            HTTPException: If allowed_params is configured for this tool but arguments contain disallowed params
        """
        allowed_params: Final = server.allowed_params or {}
        matched: Final = match_known_tool_name(tool_name, server, allowed_params)
        if matched is None:
            return

        allowed_params_list: Final = allowed_params[matched]

        # Filter arguments to only include allowed parameters
        disallowed_params: Final = [param for param in arguments if param not in allowed_params_list]

        if disallowed_params:
            raise HTTPException(
                status_code=403,
                detail={
                    "error": f"Parameters {disallowed_params} are not allowed for tool {tool_name}. "
                    f"Allowed parameters: {allowed_params_list}. "
                    f"Contact proxy admin to allow these parameters."
                },
            )

    async def check_tool_permission_for_key_team(
        self,
        tool_name: str,
        server: MCPServer,
        user_api_key_auth: UserAPIKeyAuth | None,
    ) -> None:
        """
        Check if a tool is allowed based on key/team object_permission.mcp_tool_permissions.
        Uses MCPRequestHandler.is_tool_allowed_for_server for consistent inheritance logic.
        Raises HTTPException if tool is not allowed.

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Remove the disallowed parameters from the call, or ask the proxy admin to allow them.

Example fix

Call the tool using only parameters from the allowed list.

When it happens

Trigger: Thrown at litellm/proxy/_experimental/mcp_server/mcp_server_manager.py:4489 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/bd71a8717ca14d25. Report an issue: GitHub.