Signal MCP Client

An MCP (Model Context Protocol) client that uses Signal for sending and receiving messages.

Setup and start the Signal Chat Bot

These Instructions are for Ubuntu Linux. With some minor modification this should also work on other Linux Distros, Mac or Windows. I recommend to use an extra phone number for the bot, so you don't have to use your own.

1. Install uv and podman:

   sudo apt install podman
   curl -LsSf https://astral.sh/uv/install.sh | sh

2. Start the Signal CLI Rest Server container:

   mkdir -p $HOME/.local/share/signal-api
   podman run \
       --name signal-cli-api \
       --replace \
       -p 8080:8080 \
       -v $HOME/.local/share/signal-api:/home/.local/share/signal-cli \
       -e 'MODE=json-rpc' \
       docker.io/bbernhard/signal-cli-rest-api:latest-dev

3. Connect the signal-cli-rest-api container to your signal account by opening this link and scanning the QR code:

   http://localhost:8080/v1/qrcodelink?device_name=signal-api
   

4. Create a config.json with your mcp servers. For example for testing you can use:

   cat << EOF > config.json
   {
       "servers": [{
           "name": "echo-mcp-server-for-testing",
           "command": "uvx",
           "args": ["echo-mcp-server-for-testing"],
           "env": {"SECRET_KEY": "123456789"}
       }]
   }
   EOF

5. Create a session directory for saving the message history, images, videos and settings for each user and start the MCP client:

   export ANTHROPIC_API_KEY='your-key'
   export SIGNAL_PHONE_NUMBER='+1234567890'
   export FAL_KEY='your-key' # optional for transcribing voice messages
   
   uvx signal-mcp-client \
       --config config.json \
       --session-save-dir /absolute/path/to/session/dir \
       --available-models claude-3-7-sonnet-latest claude-3-5-haiku-latest \
       --default-model-name claude-3-7-sonnet-latest \
       --default-system-prompt "" \
       --default-llm-chat-message-context-limit 50

Adding MCP Server

Add the MCP server in the config.json file.

Here are some example servers I use:

• vlc-mcp-server: An MCP Server to play and control local movies using VLC.
• fal-ai-mcp-server: An MCP Server to use the fal.ai APIs to generate images and videos.

Contributing

Contributions to this project are welcome. Feel free to report bugs, suggest ideas, or create merge requests.

Development

Running from source

1. Clone the repo git clone git@github.com:piebro/signal-mcp-client.git.
2. Go into the root dir cd signal-mcp-client.
3. Run the MCP client:

   export ANTHROPIC_API_KEY='your-key'
   export SIGNAL_PHONE_NUMBER='+1234567890'
   export FAL_API_KEY='your-key' # optional for transcribing voice messages
   # additional optional environment variables:
   export SIGNAL_WS_BASE_URL="ws://localhost:8080"
   export SIGNAL_HTTP_BASE_URL="http://localhost:8080" 
   export CLIENT_LOG_LEVEL="DEBUG"
   export SERVER_LOG_LEVEL="DEBUG"
   # you can also use a .env file in the root directory to set the environment variables
   
   uv run signal_mcp_client/main.py \
       --config config.json \
       --session-save-dir /absolute/path/to/session/dir \
       --available-models claude-3-7-sonnet-latest claude-3-5-haiku-latest \
       --default-model-name claude-3-7-sonnet-latest \
       --default-system-prompt "" \
       --default-llm-chat-message-context-limit 50

Formatting and Linting

The code is formatted and linted with ruff:

uv run ruff format
uv run ruff check --fix

Building with uv

Build the package using uv:

uv build

Releasing a New Version

To release a new version of the package to PyPI, create and push a new Git tag:

git tag v0.2.0
git push origin v0.2.0

Running as a Systemd Service

To ensure the Signal REST API and the MCP Client run automatically on boot and restart if they fail, you can set them up as systemd user services. User services run under your specific user account.

This setup assumes that you have completed the setup steps and your project is located at /home/$USER/signal-mcp-client.

1. Enable User Lingering to keep your user session active after logging out.

   sudo loginctl enable-linger $USER

2. Create Systemd Service Directory

   mkdir -p /home/$USER/.config/systemd/user/

3. Create Service File for Signal REST API

   cat << EOF > "/home/$USER/.config/systemd/user/signal-cli-rest-api.service"
   [Unit]
   Description=Signal CLI REST API Container
   After=network.target
   Wants=network-online.target
   
   [Service]
   Environment="XDG_RUNTIME_DIR=/run/user/%U"
   Environment="DBUS_SESSION_BUS_ADDRESS=unix:path=%t/bus"
   SyslogIdentifier=signal-cli-rest-api
   Restart=on-failure
   RestartSec=30
   
   ExecStartPre=-/usr/bin/podman stop signal-cli-api
   ExecStartPre=-/usr/bin/podman rm signal-cli-api
   
   ExecStart=/usr/bin/podman run --name signal-cli-api \\
       -p 127.0.0.1:8080:8080 \\
       --replace \\
       -v /home/$USER/.local/share/signal-api:/home/.local/share/signal-cli \\
       -e MODE=json-rpc \\
       docker.io/bbernhard/signal-cli-rest-api:latest
   
   ExecStop=/usr/bin/podman stop signal-cli-api
   
   [Install]
   WantedBy=default.target
   EOF

4. Create Service File for Signal MCP Client

   cat << EOF > "/home/$USER/.config/systemd/user/signal-mcp-client.service"
   [Unit]
   Description=Signal MCP Client Application
   After=network.target signal-cli-rest-api.service
   Wants=signal-cli-rest-api.service
   
   [Service]
   Environment="ANTHROPIC_API_KEY=your-key" 
   Environment="SIGNAL_PHONE_NUMBER=+1234567890"
   # Environment="FAL_KEY=your-key"
   # Environment="SIGNAL_WS_BASE_URL=ws://127.0.0.1:8080"
   # Environment="SIGNAL_HTTP_BASE_URL=http://127.0.0.1:8080" 
   # Environment="CLIENT_LOG_LEVEL=INFO"
   # Environment="SERVER_LOG_LEVEL=INFO"
   SyslogIdentifier=signal-mcp-client
   
   Restart=on-failure
   RestartSec=30
   
   ExecStart=/home/$USER/.local/bin/uvx signal-mcp-client \
       --config config.json \
       --session-save-dir /home/$USER/sessions \
       --available-models claude-3-7-sonnet-latest claude-3-5-haiku-latest \
       --default-model-name claude-3-7-sonnet-latest \
       --default-system-prompt "" \
       --default-llm-chat-message-context-limit 50
   
   [Install]
   WantedBy=default.target
   EOF

5. Enable and Start the Services

   systemctl --user daemon-reload
   
   systemctl --user enable signal-cli-rest-api.service
   systemctl --user enable signal-mcp-client.service
   
   systemctl --user start signal-cli-rest-api.service
   systemctl --user start signal-mcp-client.service

6. Check Service Status and Logs

   systemctl --user status signal-cli-rest-api.service
   systemctl --user status signal-mcp-client.service
   
   journalctl --user -u signal-cli-rest-api.service -f
   journalctl --user -u signal-mcp-client.service -f

License

This project is licensed under the MIT License. See the LICENSE file for details.