SwiftMCPCore

The neutral, dependency-free wire-protocol core for the Model Context Protocol, in Swift.

One Foundation-only, cross-platform module, SwiftMCPCore, that owns the JSON-RPC 2.0 + MCP value types under the MCP.Core.Protocols.* namespace: request/response/error/notification envelopes, RequestID, AnyCodable, JSONValue, content blocks, tools, resources, prompts, and client/server capabilities. The type names and JSON shapes follow the MCP specification (protocolVersion 2025-11-25).

It is only the wire types: no transport, no server runtime, no client. Independent MCP clients and servers depend on this package and add their own transport and runtime on top. A consumer that already has an MCPCore target can @_exported import SwiftMCPCore from it (the module name is intentionally distinct from MCPCore to avoid a duplicate-module clash; the MCP.Core.Protocols anchor is identical regardless, so call sites never change).

Install

.package(url: "https://github.com/mihaelamj/SwiftMCPCore.git", from: "0.1.0"),

.target(
    name: "YourMCPThing",
    dependencies: [.product(name: "SwiftMCPCore", package: "SwiftMCPCore")],
)

Use

import SwiftMCPCore

let request = MCP.Core.Protocols.Request(
    id: .int(1),
    method: "tools/call",
    params: MCP.Core.Protocols.CallToolRequest.Params(name: "list_frameworks", arguments: nil),
)
let data = try JSONEncoder().encode(request)
// ... send `data` over whatever transport you own; decode the response with
//     MCP.Core.Protocols.JSONRPCResponse / JSONRPCError.

Add transport in your own namespace, e.g. extension MCP.Core { enum Transport {} }; it deliberately does not live here.

Requirements

• Swift 6.2+
• Builds on macOS, iOS, and Linux (Foundation-only, zero dependencies).

Building

swift build
swift test

License

MIT.