Bash MCP Server

A Model Context Protocol (MCP) server that executes bash commands. Returns stdout, stderr, exit code, and execution duration for each command.

View on mpak registry | Built by NimbleBrain

Install

Install with mpak:

mpak install @nimblebraininc/bash

Claude Code

claude mcp add bash -- mpak run @nimblebraininc/bash

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "bash": {
      "command": "mpak",
      "args": ["run", "@nimblebraininc/bash"]
    }
  }
}

See the mpak registry page for full install options.

Tools

bash_exec

Execute a bash command and return stdout, stderr, exit code, and duration.

Parameter	Type	Required	Description
command	string	Yes	The bash command to execute
cwd	string	No	Working directory (defaults to server's cwd)
timeout	integer	No	Timeout in seconds (default: 30, max: 600)
env	object	No	Additional environment variables to set

Example call:

{
  "name": "bash_exec",
  "arguments": {
    "command": "ls -la /tmp",
    "timeout": 10
  }
}

Example response:

{
  "stdout": "total 0\ndrwxrwxrwt  12 root  wheel  384 Jan 15 12:00 .\ndrwxr-xr-x   6 root  wheel  192 Jan  1 00:00 ..\n",
  "stderr": "",
  "exit_code": 0,
  "duration_ms": 12
}

Security Model

This server executes arbitrary bash commands. Security is secure-by-deployment: the server itself has no allowlist or sandbox. Instead, security is enforced by the deployment environment:

• mpak: User approves MTF permissions (subprocess: "full") at install time
• Containers: Linux namespaces, cgroups, and network policies restrict what commands can do
• Claude Desktop: Runs under the user's own OS permissions

The MTF permission declaration (subprocess: "full", filesystem: "full", network: "full") accurately reflects that bash commands can read/write files and make network calls.

Quick Start

Local Development

git clone https://github.com/NimbleBrainInc/mcp-bash.git
cd mcp-bash

# Install dependencies
uv sync

# Run the server (stdio mode)
uv run python -m mcp_bash.server

# Or run via FastMCP
uv run fastmcp run src/mcp_bash/server.py

The server supports HTTP transport with:

• Health check: GET /health
• MCP endpoint: POST /mcp

Development

# Install with dev dependencies
uv sync --group dev

# Run unit tests
make test

# Run with coverage
make test-cov

# Run all checks (format, lint, typecheck, unit tests)
make check

# Format
uv run ruff format .

# Lint
uv run ruff check .

E2E Tests

End-to-end tests validate the full MCPB bundle lifecycle: building the bundle, deploying it into a Docker container, and calling tools over HTTP.

Prerequisites: Docker running, mcpb CLI installed (npm install -g @anthropic-ai/mcpb)

make test-e2e

The tests:

1. Vendor dependencies for the Docker container's Linux architecture
2. Build a .mcpb bundle with mcpb pack
3. Serve the bundle over HTTP
4. Start a nimbletools/mcpb-python container that downloads and runs the bundle
5. Verify the /health endpoint, MCP tool listing, and tool invocation via streamable HTTP

About

Bash MCP Server is published on the mpak registry and built by NimbleBrain. mpak is an open registry for Model Context Protocol servers.

• mpak registry
• NimbleBrain
• MCP specification
• Discord community

License

MIT