Crate rmcp 

rmcp

The official Rust SDK for the Model Context Protocol. Build MCP servers that expose tools, resources, and prompts to AI assistants — or build clients that connect to them.

For getting started, usage guides, and full MCP feature documentation (resources, prompts, sampling, roots, logging, completions, subscriptions, etc.), see the main README.

Feature Flags

Feature	Description	Default
server	Server functionality and the tool system	✅
client	Client functionality
macros	#[tool] / #[prompt] macros (re-exports rmcp-macros)	✅
schemars	JSON Schema generation for tool definitions
auth	OAuth 2.0 authentication support
elicitation	Elicitation support

Transport features

Feature	Description
transport-io	Server-side stdio transport
transport-child-process	Client-side stdio transport (spawns a child process)
transport-async-rw	Generic async read/write transport
transport-streamable-http-client	Streamable HTTP client (transport-agnostic)
transport-streamable-http-client-reqwest	Streamable HTTP client with default reqwest backend
transport-streamable-http-server	Streamable HTTP server transport

TLS backend options (for HTTP transports)

Feature	Description
reqwest	Uses rustls — pure Rust TLS (recommended default)
reqwest-native-tls	Uses platform-native TLS (OpenSSL / Secure Transport / SChannel)
reqwest-tls-no-provider	Uses rustls without a default crypto provider (bring your own)

Transports

The transport layer is pluggable. Two built-in pairs cover the most common cases:

	Client	Server
stdio	TokioChildProcess	stdio
Streamable HTTP	StreamableHttpClientTransport	StreamableHttpService

Any type that implements the Transport trait can be used. The IntoTransport helper trait provides automatic conversions from:

1. (Sink, Stream) or a combined Sink + Stream
2. (AsyncRead, AsyncWrite) or a combined AsyncRead + AsyncWrite
3. A Worker implementation
4. A Transport implementation directly

License

This project is licensed under the terms specified in the repository’s LICENSE file.

Re-exports

pub use error::ErrorData;

pub use handler::client::ClientHandler;client

pub use handler::server::ServerHandler;server

pub use handler::server::wrapper::Json;server

pub use service::Peer;client or server

pub use service::Service;client or server

pub use service::ServiceError;client or server

pub use service::ServiceExt;client or server

pub use service::RoleClient;client

pub use service::serve_client;client

pub use service::RoleServer;server

pub use service::serve_server;server

pub use schemars;server or schemars

pub use serde;macros

pub use serde_json;macros

Modules

handler

model

Basic data types in MCP specification

serviceclient or server

task_managerserver

transportclient or server

Transport

Macros

const_string

elicit_safeelicitation

Macro to mark types as safe for elicitation by verifying they generate object schemas.

objectmacros

Use this macro just like serde_json::json!

pastemacros and server

Enums

RmcpError

This is an unified error type for the errors could be returned by the service.

Type Aliases

ErrorDeprecated

Attribute Macros

promptmacros and server

prompt

prompt_handlermacros and server

prompt_handler

prompt_routermacros and server

prompt_router

task_handlermacros and server

task_handler

toolmacros and server

tool

tool_handlermacros and server

tool_handler

tool_routermacros and server

tool_router