mcp -proxy

mcp-server-proxy is a proxy that translates the MCP SSE transport into standard HTTP requests/responses. It lets MCP clients connect via SSE to a configured target HTTP endpoint, making it easier to experiment with and observe MCP interactions without needing specialized SSE tooling in the client. The proxy provides two useful commands: inspect, which lets you observe the raw requests and responses between a client and a target, and serve, which starts a proxy that forwards MCP calls to a target HTTP server while exposing them as normal HTTP requests/responses. The example in the repository demonstrates an echo service that handles initialize, tools/list, and tools/call endpoints by translating them into conventional HTTP interactions. To use it, install the binary, run the proxy with a local URL and a target URL, and then configure your MCP client to point at the local proxy URL using the SSE transport type.

Prerequisites:

• Go toolchain installed (https://golang.org/dl/)
• GOPATH/bin is in your system PATH so the mcp-server-proxy binary can be found after installation

Install the MCP Server Proxy:

# Install the latest release of mcp-server-proxy
go install github.com/leizongmin/mcp-server-proxy@latest

Verify installation:

mcp-server-proxy --version

Usage (examples):

• Inspect mode (observe requests/responses without forwarding):

mcp-server-proxy inspect http://localhost:8080 http://example.com

• Serve mode (start the proxy and forward to the target):

mcp-server-proxy serve http://localhost:8080 http://example.com

Notes:

• Ensure the local URL you pass is reachable by the client, and the target URL is the MCP-enabled HTTP endpoint you want to proxy to.
• The proxy translates MCP SSE calls to standard HTTP requests, so any HTTP client library can be used on the target side.

Tips and common issues:

• If you change the target MCP server, update the proxy's target URL accordingly to maintain connectivity.
• Use the inspect command to debug mismatches between the MCP client's expected protocol and the actual HTTP requests the target receives.
• The proxy currently supports initialize, tools/list, and tools/call as shown in the example; if you extend or customize the target, ensure the HTTP endpoints conform to the expected MCP request/response shapes.
• When running in containerized environments, ensure proper network access between the local proxy URL and the target URL.
• If you encounter permission errors on binary execution, confirm that GOPATH/bin or the Go install path is included in your PATH.