Crate mcpkit_core 

mcp-core

Core types and traits for the Model Context Protocol (MCP) SDK.

This crate provides the foundational building blocks for the MCP SDK:

• Protocol types: JSON-RPC 2.0 request/response/notification types
• MCP types: Tools, resources, prompts, tasks, content, sampling, elicitation
• Capability negotiation: Client and server capabilities
• Error handling: Unified McpError type with rich diagnostics
• Typestate connection: Compile-time enforced connection lifecycle

This crate is runtime-agnostic and does not depend on any async runtime. It can be used with Tokio, smol, or any other executor.

Protocol Version

This crate implements MCP protocol version 2025-11-25.

Example

use mcpkit_core::{
    types::{Tool, ToolOutput, Content},
    capability::{ServerCapabilities, ServerInfo},
    state::Connection,
};

// Create a tool definition
let tool = Tool::new("search")
    .description("Search the database")
    .input_schema(serde_json::json!({
        "type": "object",
        "properties": {
            "query": { "type": "string" }
        },
        "required": ["query"]
    }));

// Create server capabilities
let caps = ServerCapabilities::new()
    .with_tools()
    .with_resources()
    .with_tasks();

// Create server info
let info = ServerInfo::new("my-server", "1.0.0");

Feature Flags

This crate currently has no optional features. All functionality is included by default.

Re-exports

pub use capability::ClientCapabilities;

pub use capability::ClientInfo;

pub use capability::InitializeRequest;

pub use capability::InitializeResult;

pub use capability::PROTOCOL_VERSION;

pub use capability::SUPPORTED_PROTOCOL_VERSIONS;

pub use capability::ServerCapabilities;

pub use capability::ServerInfo;

pub use capability::VersionNegotiationResult;

pub use capability::is_version_supported;

pub use capability::negotiate_version;

pub use capability::negotiate_version_detailed;

pub use error::JsonRpcError;

pub use error::McpError;

pub use error::McpResultExt;

pub use protocol::Message;

pub use protocol::Notification;

pub use protocol::ProgressToken;

pub use protocol::Request;

pub use protocol::RequestId;

pub use protocol::Response;

pub use protocol_version::ProtocolVersion;

pub use state::Closing;

pub use state::Connected;

pub use state::Connection;

pub use state::Disconnected;

pub use state::Initializing;

pub use state::Ready;

Modules

auth

OAuth 2.1 Authorization for MCP.

capability

Capability flags for MCP clients and servers.

debug

Debug and tracing utilities for MCP protocol development.

error

Unified error handling for the MCP SDK.

extension

Protocol extension infrastructure.

prelude

Prelude module for convenient imports.

protocol

JSON-RPC 2.0 protocol types for the Model Context Protocol.

protocol_version

Protocol version types and negotiation.

schema

JSON Schema utilities for MCP type validation.

state

Typestate pattern for connection lifecycle management.

types

MCP-specific types for tools, resources, prompts, tasks, and content.