MCPC

A pure Swift macOS Model Context Protocol (MCP) client. MCPC connects to MCP servers configured in config.toml over stdio, HTTP/SSE, or WebSocket transports. The only Python in this repository is the optional bundled test-server/ used for integration tests.

It ships as libraries and executables:

| Product | Description | |---------|-------------| | MCPC | Core library: config, transports, session, CLI parsing, Cursor sync | | MCPClientGUICore | GUI model and JSON argument helpers (testable without SwiftUI) | | mcpc | Command-line client for scripting and automation | | mcpc-gui | macOS SwiftUI app (MCP Client) for interactive exploration |

Requirements

macOS 14+
Swift 6.0+
uv — only needed to run make test (bundled Python test server)

Quick start

git clone <repo-url> mcpc && cd mcpc
swift build

# List configured servers
swift run mcpc list-servers

# Talk to the bundled test server (default in config.toml)
swift run mcpc ping
swift run mcpc list-tools
swift run mcpc call-tool echo --message "hello"

# Run all tests: unit tests + CLI + SSE integration (requires uv)
make test

# Launch the GUI
./scripts/run_gui.sh

# Build a distributable DMG (release MCP Client.app + installer image in dist/)
make dmg

Run commands from the project root so relative paths in the repo config.toml (for example test-server/) resolve correctly.

Configuration

All servers and client settings live in config.toml. See docs/USER_GUIDE.md for full configuration examples.

Development vs production

| Context | Config location | Logs | |---------|-----------------|------| | Repo / CLI dev | ./config.toml in the project root (or MCPC_CONFIG) | [logging].destination = "stderr" (default) | | MCP Client GUI (DMG) | ~/.mcpc/config.toml — created on first launch | ~/.mcpc/mcpc.log when destination = "file" | | CLI without local config | ~/.mcpc/config.toml — auto-created if missing | Per [logging] in that file |

The GUI always loads ~/.mcpc/config.toml by default. The CLI resolves: --config → MCPC_CONFIG → ./config.toml → ~/.mcpc/config.toml.

[app]
name = "mcpc"
version = "1.0.0"

[client]
default_server = "test-server"
protocol_version = "2024-11-05"
request_timeout_seconds = 120

[logging]
level = "info"
destination = "stderr"

[[servers]]
name = "test-server"
transport = "stdio"
command = "uv"
args = ["run", "--directory", "test-server", "python", "server.py"]
env = { PYTHONUNBUFFERED = "1" }

For production use, edit ~/.mcpc/config.toml (or launch MCP Client once to create it) and point [[servers]] at any stdio, HTTP/SSE, or WebSocket MCP server — see docs/USER_GUIDE.md.

Override the config path with --config, set MCPC_CONFIG, or use Choose config.toml… in the GUI sidebar.

CLI commands

mcpc list-servers
mcpc ping
mcpc list-tools
mcpc list-resources
mcpc list-prompts
mcpc call-tool <name> [--key value ...]
mcpc read-resource <uri>
mcpc get-prompt <name> [--key value ...]

Use -s <name> to select a server, or rely on client.default_server.

Makefile targets

| Target | Description | |--------|-------------| | make build | Debug build of all products | | make test | Unit tests + CLI + SSE integration | | make test-unit | swift test only | | make gui | Launch mcpc-gui | | make app | Build dist/MCP Client.app (release) | | make dmg | Build distributable DMG installer | | make install | Install CLI and GUI to $(PREFIX)/bin |

Project layout

mcpc/
├── config.toml              # Dev/test configuration (repo root)
├── Package.swift            # Swift package manifest
├── Sources/
│   ├── MCPC/                # Core library (config, ~/.mcpc, transports, session, MCPCLI)
│   ├── MCPClientGUICore/    # GUI model (MCPAppModel)
│   ├── MCPClientCLI/        # mcpc CLI
│   └── MCPClientGUI/        # mcpc-gui SwiftUI views
├── test-server/             # Python FastMCP server for integration tests
├── packaging/               # App bundle templates and DMG extras
├── Tests/
│   ├── MCPCTests/           # Config, CLI parser, Cursor import/sync unit tests
│   └── MCPClientGUITests/   # GUI model + live-server integration tests
├── scripts/
│   ├── test_all.sh
│   ├── test_swift_client.sh
│   ├── test_cli.sh
│   ├── test_sse_client.sh
│   ├── run_gui.sh
│   ├── package_app.sh
│   └── create_dmg.sh
└── docs/
    ├── SPEC.md              # Technical specification
    ├── USER_GUIDE.md        # End-user documentation
    └── HLD.md               # High-level design

Documentation

| Document | Audience | Contents | |----------|----------|----------| | docs/SPEC.md | Implementers | Config schema, MCP coverage, tests, packaging, error model | | docs/USER_GUIDE.md | Users | Installation, testing, configuration, CLI/GUI, troubleshooting | | docs/HLD.md | Architects | Component diagram, data flow, transports, test and packaging design |

Dependencies

SwiftMCPClient — MCP protocol implementation
TOMLKit — config.toml parsing
swift-log — logging (GUI)

License

See repository license file if present.

MCP Servers