Crate mcp_kit 

mcp — Rust library for building MCP servers

A high-quality, type-safe, async-first library for the Model Context Protocol.

Quick start

use mcp_kit::prelude::*;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    McpServer::builder()
        .name("my-server")
        .version("1.0.0")
        .tool(
            Tool::new("greet", "Say hello", serde_json::json!({
                "type": "object",
                "properties": { "name": { "type": "string" } },
                "required": ["name"]
            })),
            |args: serde_json::Value| async move {
                CallToolResult::text(format!("Hello, {}!", args["name"]))
            },
        )
        .build()
        .serve_stdio()
        .await?;
    Ok(())
}

Re-exports

pub use error::ErrorCode;

pub use error::ErrorData;

pub use error::McpError;

pub use error::McpResult;

pub use protocol::JsonRpcError;

pub use protocol::JsonRpcMessage;

pub use protocol::JsonRpcNotification;

pub use protocol::JsonRpcRequest;

pub use protocol::JsonRpcResponse;

pub use protocol::ProgressToken;

pub use protocol::RequestId;

pub use protocol::JSONRPC_VERSION;

pub use protocol::MCP_PROTOCOL_VERSION;

pub use types::content::AudioContent;

pub use types::content::BlobResourceContents;

pub use types::content::Content;

pub use types::content::EmbeddedResource;

pub use types::content::ImageContent;

pub use types::content::ResourceContents;

pub use types::content::TextContent;

pub use types::content::TextResourceContents;

pub use types::elicitation::ElicitAction;

pub use types::elicitation::ElicitRequest;

pub use types::elicitation::ElicitResult;

pub use types::elicitation::ElicitSchema;

pub use types::messages::CallToolRequest;

pub use types::messages::CompleteRequest;

pub use types::messages::CompleteResult;

pub use types::messages::CompletionArgument;

pub use types::messages::CompletionReference;

pub use types::messages::GetPromptRequest;

pub use types::messages::GetPromptResult;

pub use types::messages::InitializeRequest;

pub use types::messages::InitializeResult;

pub use types::messages::ListPromptsResult;

pub use types::messages::ListResourcesResult;

pub use types::messages::ListToolsResult;

pub use types::messages::ReadResourceRequest;

pub use types::messages::ReadResourceResult;

pub use types::prompt::Prompt;

pub use types::prompt::PromptArgument;

pub use types::prompt::PromptMessage;

pub use types::prompt::PromptMessageRole;

pub use types::resource::Resource;

pub use types::resource::ResourceTemplate;

pub use types::sampling::CreateMessageRequest;

pub use types::sampling::CreateMessageResult;

pub use types::sampling::ModelPreferences;

pub use types::sampling::SamplingMessage;

pub use types::tool::CallToolResult;

pub use types::tool::Tool;

pub use types::tool::ToolAnnotations;

pub use types::ClientCapabilities;

pub use types::ClientInfo;

pub use types::Implementation;

pub use types::LoggingLevel;

pub use types::ServerCapabilities;

pub use types::ServerInfo;

pub use server::builder::McpServerBuilder;

pub use server::builder::PromptDef;

pub use server::builder::ResourceDef;

pub use server::builder::ToolDef;

pub use server::core::McpServer;

pub use server::elicitation::ChannelElicitationClient;

pub use server::elicitation::ElicitationClient;

pub use server::elicitation::ElicitationClientExt;

pub use server::elicitation::ElicitationError;

pub use server::elicitation::ElicitationRequestBuilder;

pub use server::extract::Extension;

pub use server::extract::Json;

pub use server::extract::State;

pub use server::handler::CompletionHandler;

pub use server::handler::IntoToolResult;

pub use server::handler::ToolHandler;

pub use server::notification::NotificationReceiver;

pub use server::notification::NotificationSender;

pub use server::notification::SendError;

pub use server::notification::SharedNotificationSender;

pub use server::progress::ProgressTokenExt;

pub use server::progress::ProgressTracker;

pub use server::session::Session;

pub use server::Auth;

pub use server::AuthenticatedMarker;

pub use auth::AuthProvider;

pub use auth::AuthenticatedIdentity;

pub use auth::CompositeAuthProvider;

pub use auth::Credentials;

pub use auth::DynAuthProvider;

pub use auth::IntoDynProvider;

pub use auth::BearerTokenProvider;

pub use auth::ApiKeyProvider;

pub use auth::BasicAuthProvider;

pub use auth::CustomHeaderProvider;

pub use transport::stdio::ServeStdioExt;

pub use transport::stdio::StdioTransport;

pub use transport::sse::ServeSseExt;

pub use transport::sse::SseTransport;

pub use transport::streamable::ServeStreamableExt;

pub use transport::streamable::StreamableTransport;

pub use transport::websocket::ServeWebSocketExt;

pub use transport::websocket::WebSocketTransport;

pub use schemars;

pub use serde_json;

pub use tokio;

Modules

auth

Authentication support for MCP servers.

error

plugin

Plugin system for dynamically loading and managing MCP tools, resources, and prompts.

prelude

Everything you need to build an MCP server — import with use mcp_kit::prelude::*.

protocol

server

transport

types

Traits

Deserialize

A data structure that can be deserialized from any data format supported by Serde.

JsonSchema

A type which can be described as a JSON Schema document.

Serialize

A data structure that can be serialized into any data format supported by Serde.

Attribute Macros

prompt

Marks an async function as an MCP prompt handler and generates a companion {fn_name}_prompt_def() function that returns a mcp::PromptDef.

resource

Marks an async function as an MCP resource handler and generates a companion {fn_name}_resource_def() function that returns a mcp::ResourceDef.

tool

Marks an async function as an MCP tool and generates a companion {fn_name}_tool_def() function that returns a mcp::ToolDef.

Derive Macros

Deserialize

JsonSchema

Serialize