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MCPX_DOCKER_NO_PERMISSION

Severity: error Domain: Docker

What happened​

The Docker daemon is up, but the user mcpproxy is running as does not have permission to connect to the Docker socket (/var/run/docker.sock on Linux/macOS).

How to fix​

Linux — add the user to the docker group​

sudo usermod -aG docker "$USER"
newgrp docker          # apply in the current shell without logging out
docker info            # verify

You may need to log out and back in for GUI apps (the tray) to pick up the new group.

macOS — check Docker Desktop permissions​

Docker Desktop usually grants access automatically. If not:

  • Reinstall Docker Desktop (it re-creates the socket symlink with the right perms).
  • Or use Colima, which runs as the current user without socket-permission issues.

Rootless Docker​

If you're using rootless Docker, make sure DOCKER_HOST points at the rootless socket and the systemd user service is running:

systemctl --user status docker
echo "$DOCKER_HOST"     # typically unix:///run/user/<uid>/docker.sock

Avoid setuid hacks​

Don't chmod 666 /var/run/docker.sock — that gives every local process root escalation via Docker. Adding the user to the docker group is the safe, canonical fix (and is documented to grant root-equivalent privileges).