Bridge Rust code to LLMs without boilerplate wiring

What it does RMCP implements the Model Context Protocol in Rust, letting you build servers that expose functions, files, and prompts to MCP-compatible clients, or write clients that consume them. The core crate manages protocol framing and tokio-based transport, while a companion macro crate generates routing and JSON Schema from your structs.

The interesting bit The #[tool], #[prompt], and #[tool_router] macros handle the drudgery of schema derivation and capability negotiation. For a simple tools-only server, #[tool_router(server_handler)] generates a complete ServerHandler implementation from an impl block, so you never touch the wire protocol directly.

Key highlights

• Dual client/server support over stdio or child-process transports
• Automatic JSON Schema 2020-12 generation from serde/schemars structs
• #[tool_router(server_handler)] eliminates manual ServerHandler boilerplate for tool-only servers
• Client-side helpers automatically paginate through list_all_tools and list_all_resources
• Supports notifications, resource templates, and long-running tasks

Caveats

• Macro-generated schemas ignore struct-level documentation, deriving descriptions solely from field names, types, and field docs
• A 1.x release with breaking changes is in progress; the repository links to a migration guide
• Hard-wired to the tokio runtime; there is no abstraction for other async executors

Verdict Pick this up if you want to serve Rust logic to MCP-compatible clients without writing protocol glue. Skip it if you are on a non-tokio runtime or need a generic RPC framework rather than MCP specifically.