From 4e7a916b6d344267109266204159dbb6b72623d9 Mon Sep 17 00:00:00 2001 From: Tim Kellogg Date: Fri, 18 Apr 2025 08:15:40 -0400 Subject: [PATCH] Added note on how stderr is handled in clients --- README.md | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/README.md b/README.md index a27c58fa5..03748d3f8 100644 --- a/README.md +++ b/README.md @@ -66,6 +66,7 @@ FastMCP handles the complex protocol details and server management, letting you - [Proxy Servers](#proxy-servers) - [Composing MCP Servers](#composing-mcp-servers) - [OpenAPI \& FastAPI Generation](#openapi--fastapi-generation) + - [Handling `stderr`](#handling-stderr) - [Running Your Server](#running-your-server) - [Development Mode (Recommended for Building \& Testing)](#development-mode-recommended-for-building--testing) - [Claude Desktop Integration (For Regular Use)](#claude-desktop-integration-for-regular-use) @@ -666,6 +667,12 @@ mcp_server = FastMCP.from_openapi(openapi_spec, client=http_client) if __name__ == "__main__": mcp_server.run() ``` + +### Handling `stderr` +The MCP spec allows for the server to write anything it wants to `stderr`, and it +doesn't specify the format in any way. FastMCP will forward the server's `stderr` +to the client's `stderr`. + ## Running Your Server Choose the method that best suits your needs: