Crate pmcp 

MCP SDK for Rust

A high-quality Rust implementation of the Model Context Protocol (MCP) SDK.

This crate provides both client and server implementations of MCP with:

• Full protocol compatibility with the TypeScript SDK
• Zero-copy parsing where possible
• Comprehensive type safety
• Multiple transport options (stdio, HTTP/SSE, WebSocket)
• Built-in authentication support

Quick Start

Client Example

use pmcp::{Client, StdioTransport, ClientCapabilities};

// Create a client with stdio transport
let transport = StdioTransport::new();
let mut client = Client::new(transport);

// Initialize the connection
let server_info = client.initialize(ClientCapabilities::default()).await?;

// List available tools
let tools = client.list_tools(None).await?;

Server Example

use pmcp::{Server, ServerCapabilities, ToolHandler};
use async_trait::async_trait;
use serde_json::Value;

struct MyTool;

#[async_trait]
impl ToolHandler for MyTool {
    async fn handle(&self, args: Value, _extra: pmcp::RequestHandlerExtra) -> Result<Value, pmcp::Error> {
        Ok(serde_json::json!({"result": "success"}))
    }
}

let server = Server::builder()
    .name("my-server")
    .version("1.0.0")
    .capabilities(ServerCapabilities::default())
    .tool("my-tool", MyTool)
    .build()?;

// Run with stdio transport
server.run_stdio().await?;

Re-exports

pub use client::Client;

pub use client::ClientBuilder;

pub use client::ToolCallResponse;

pub use error::Error;

pub use error::ErrorCode;

pub use error::Result;

pub use server::cancellation::RequestHandlerExtra;Non-WebAssembly

pub use server::task_store::InMemoryTaskStore;Non-WebAssembly

pub use server::task_store::StoreConfig;Non-WebAssembly

pub use server::task_store::TaskStore;Non-WebAssembly

pub use server::task_store::TaskStoreError;Non-WebAssembly

pub use server::auth;Non-WebAssembly

pub use server::simple_prompt::SimplePrompt;Non-WebAssembly

pub use server::simple_prompt::SyncPrompt;Non-WebAssembly

pub use server::simple_resources::DynamicResourceHandler;Non-WebAssembly

pub use server::simple_resources::ResourceCollection;Non-WebAssembly

pub use server::simple_resources::StaticResource;Non-WebAssembly

pub use server::simple_tool::SimpleTool;Non-WebAssembly

pub use server::simple_tool::SyncTool;Non-WebAssembly

pub use server::state::State;Non-WebAssembly

pub use server::typed_prompt::TypedPrompt;Non-WebAssembly

pub use server::typed_tool::SimpleToolExt;Non-WebAssembly

pub use server::typed_tool::SyncToolExt;Non-WebAssembly

pub use server::typed_tool::TypedSyncTool;Non-WebAssembly

pub use server::typed_tool::TypedTool;Non-WebAssembly

pub use server::typed_tool::TypedToolWithOutput;Non-WebAssembly

pub use server::ui::UIResourceBuilder;Non-WebAssembly

pub use server::McpServer;Non-WebAssembly

pub use server::PromptHandler;Non-WebAssembly

pub use server::ResourceHandler;Non-WebAssembly

pub use server::SamplingHandler;Non-WebAssembly

pub use server::Server;Non-WebAssembly

pub use server::ServerBuilder;Non-WebAssembly

pub use server::ToolHandler;Non-WebAssembly

pub use shared::StdioTransport;Non-WebAssembly

pub use server::tower_layers::AllowedOrigins;streamable-http

pub use server::tower_layers::DnsRebindingLayer;streamable-http

pub use server::tower_layers::SecurityHeadersLayer;streamable-http

pub use shared::batch::BatchRequest;

pub use shared::batch::BatchResponse;

pub use shared::uri_template::UriTemplate;

pub use shared::AuthMiddleware;

pub use shared::LoggingMiddleware;

pub use shared::Middleware;

pub use shared::MiddlewareChain;

pub use shared::RetryMiddleware;

pub use shared::Transport;

pub use shared::WebSocketConfig;websocket and non-WebAssembly

pub use shared::WebSocketTransport;websocket and non-WebAssembly

pub use shared::HttpConfig;http and non-WebAssembly

pub use shared::HttpTransport;http and non-WebAssembly

pub use types::AuthInfo;

pub use types::AuthScheme;

pub use types::CallToolRequest;

pub use types::CallToolResult;

pub use types::ClientCapabilities;

pub use types::ClientNotification;

pub use types::ClientRequest;

pub use types::CompleteRequest;

pub use types::CompleteResult;

pub use types::CompletionArgument;

pub use types::CompletionReference;

pub use types::Content;

pub use types::CreateMessageParams;

pub use types::CreateMessageResult;

pub use types::GetPromptResult;

pub use types::Implementation;

pub use types::IncludeContext;

pub use types::ListResourcesResult;

pub use types::ListToolsResult;

pub use types::LoggingLevel;

pub use types::ModelPreferences;

pub use types::ProgressNotification;

pub use types::ProgressToken;

pub use types::PromptMessage;

pub use types::ProtocolVersion;

pub use types::ReadResourceResult;

pub use types::RequestId;

pub use types::ResourceInfo;

pub use types::Role;

pub use types::RootsCapabilities;

pub use types::SamplingCapabilities;

pub use types::SamplingMessage;

pub use types::ServerCapabilities;

pub use types::ServerNotification;

pub use types::ServerRequest;

pub use types::TokenUsage;

pub use types::ToolCapabilities;

pub use types::ToolInfo;

pub use types::UIMimeType;

pub use types::UIResource;

pub use types::UIResourceContents;

pub use types::CallToolResult as ToolResult;

pub use utils::BatchingConfig;Non-WebAssembly

pub use utils::DebouncingConfig;Non-WebAssembly

pub use utils::MessageBatcher;Non-WebAssembly

pub use utils::MessageDebouncer;Non-WebAssembly

pub use types::protocol::version::negotiate_protocol_version;

pub use types::protocol::version::DEFAULT_PROTOCOL_VERSION;

pub use types::protocol::version::LATEST_PROTOCOL_VERSION;

pub use types::protocol::version::SUPPORTED_PROTOCOL_VERSIONS;

Modules

assets

Platform-agnostic asset loading for MCP servers.

axumstreamable-http

Axum Router convenience API for secure MCP server hosting.

client

MCP client implementation.

compositioncomposition

MCP Server Composition

error

Error types for the MCP SDK.

runtime

Runtime abstraction layer for platform-independent async execution

server

MCP server implementation.

shared

Shared components used by both client and server.

simdsimd

SIMD optimizations for PMCP performance-critical operations Provides vectorized implementations of JSON parsing and string operations

types

Core protocol types for MCP.

utils

Utility modules for the MCP SDK.

Macros

context_or_new

Macro to get current context or create new one.

debug_correlated

Log debug with correlation.

error_correlated

Log error with correlation.

info_correlated

Log info with correlation.

log_correlated

Helper macros for correlated logging.

warn_correlated

Log warning with correlation.

with_context

Macro to run code with request context.

Constants

DEFAULT_REQUEST_TIMEOUT_MS

Default request timeout in milliseconds

Functions

log

Server-side logging function (placeholder for examples).

Attribute Macros

async_trait

mcp_promptmacros

Defines a prompt handler with automatic argument schema generation.

mcp_servermacros

Collects #[mcp_tool] methods from an impl block and generates tool handlers.

mcp_toolmacros

Defines an MCP tool with automatic schema generation and state injection.