mcp-local-router

# MCP Local Router This project is an MCP (Model Context Protocol) local router that serves as an aggregation proxy for MCP servers. It can connect to multiple upstream MCP servers and aggregate their functionalities into a single interface for downstream clients. ## Features - Supports specifying a configuration file via command line arguments - Supports configuring multiple upstream MCP servers - Supports stdio transport - Supports injecting environment variables into stdio transport - Supports SSE transport with aggregated `/sse` and per-upstream `/sse/{serverName}` endpoints ## Usage ### Running It must be run with a configuration file: ```bash cargo run -- --config mcp-config.json --transport sse ``` #### SSE Routing When the router runs with `--transport sse`, it exposes two kinds of endpoints: - `/sse` streams the aggregated tool surface area from every configured upstream server. - `/sse/{serverName}` streams only the tools from a single upstream. The `{serverName}` segment must match the key from `mcpServers` in your configuration file (for example `/sse/filesystem` or `/sse/workspace-search`). The server name keys should be URL-safe because they are used directly as path segments. Each SSE connection emits an initial `endpoint` event containing the HTTP path clients should use for `POST` requests. All streaming endpoints share the same `POST /message?sessionId=…` channel. ### Configuration File Format The configuration file is in JSON format; an example is shown below: ```json { "mcpServers": { "filesystem": { "command": "npx", "args": [ "-y", "@modelcontextprotocol/server-filesystem", "/Users/username/Desktop" ], "env": { "LINEAR_ACCESS_TOKEN": "your_personal_access_token" } }, "workspace-search": { "command": "npx", "args": [ "-y", "@modelcontextprotocol/server-everything" ], "env": {} } } } ``` Description: - mcpServers: a mapping of multiple server configurations - Each key is the server's name (used for logging and the `/sse/{serverName}` path) - Each value is an object containing the following fields: - command: the command to execute - args: an array of command arguments - env: a mapping of environment variables to inject ## Build and Installation ```bash # Build the project cargo build --release # Run cargo run --release -- --config mcp-config.json --transport stdio ``` ## Dependencies - Rust 2021 Edition - tokio async runtime - MCP-related libraries: [rmcp](https://github.com/modelcontextprotocol/rust-sdk)