Bazel MCP

Bazel MCP

A Model Context Protocol server that exposes Bazel build system capabilities to AI assistants.

Repo: github.com/saeid-rez/bazel-mcp

Tools

Tool	Description
bazel_query	Run arbitrary bazel query expressions
bazel_cquery	Run configured bazel cquery expressions (select() and platforms)
bazel_aquery	Run action bazel aquery expressions (compiler flags, commands)
list_targets	List targets in a package or subtree
get_deps	Direct or transitive dependencies of a target
get_rdeps	Reverse dependencies within a scope
show_target_info	Rule definition via query --output=build
find_affected_targets	Find targets affected by changed files
bazel_build	Run bazel build with structured failure diagnostics
bazel_test	Run bazel test with structured target and failed-case results
bazel_run	Run bazel run with arguments, environment variables, and working directory controls
explain_build_file	Read BUILD file contents for analysis

Usage

Requires uv. Configure the server with a Bazel workspace path if your MCP client does not start it from that workspace.

Antigravity (agy)

Add the following to ~/.gemini/config/mcp_config.json:

{
  "mcpServers": {
    "bazel": {
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/saeid-rez/bazel-mcp",
        "bazel-mcp-server"
      ]
    }
  }
}

Bazel commands run in your active workspace by default. If Antigravity does not start the server from your Bazel workspace, pass --workspace-root explicitly:

{
  "mcpServers": {
    "bazel": {
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/saeid-rez/bazel-mcp",
        "bazel-mcp-server",
        "--workspace-root",
        "/path/to/your/bazel/workspace"
      ]
    }
  }
}

OpenCode

Add the following to opencode.json or opencode.jsonc. Replace /path/to/your/bazel/workspace with the absolute path to your Bazel workspace.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "bazel": {
      "type": "local",
      "command": [
        "uvx",
        "--from",
        "git+https://github.com/saeid-rez/bazel-mcp",
        "bazel-mcp-server",
        "--workspace-root",
        "/path/to/your/bazel/workspace"
      ],
      "enabled": true
    }
  }
}

GitHub Copilot CLI

Add the following to ~/.copilot/mcp-servers.json. Replace /path/to/your/bazel/workspace with the absolute path to your Bazel workspace.

{
  "mcp": {
    "servers": {
      "bazel": {
        "command": "uvx",
        "args": [
          "--from",
          "git+https://github.com/saeid-rez/bazel-mcp",
          "bazel-mcp-server",
          "--workspace-root",
          "/path/to/your/bazel/workspace"
        ],
        "protocol": "stdio"
      }
    }
  }
}

Alternatively, run /mcp add bazel inside Copilot CLI and provide the same command and arguments.

Install With uv

To install the server persistently instead of running it from GitHub, run:

uv tool install bazel-mcp-server

Then use the following installed-server configuration in place of the GitHub-based command above. Include --workspace-root and its path when the client does not start the server from the Bazel workspace.

Antigravity (agy):

{
  "mcpServers": {
    "bazel": {
      "command": "bazel-mcp-server",
      "args": ["--workspace-root", "/path/to/your/bazel/workspace"]
    }
  }
}

OpenCode:

{
  "mcp": {
    "bazel": {
      "type": "local",
      "command": ["bazel-mcp-server", "--workspace-root", "/path/to/your/bazel/workspace"],
      "enabled": true
    }
  }
}

GitHub Copilot CLI:

{
  "mcp": {
    "servers": {
      "bazel": {
        "command": "bazel-mcp-server",
        "args": ["--workspace-root", "/path/to/your/bazel/workspace"],
        "protocol": "stdio"
      }
    }
  }
}

Cursor

Add this to .cursor/mcp.json in the Bazel workspace.

{
  "mcpServers": {
    "bazel": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/saeid-rez/bazel-mcp", "bazel-mcp-server"]
    }
  }
}

Bazel commands run in your open workspace by default.

If Cursor does not start the server from the Bazel workspace, pass the workspace explicitly:

{
  "mcpServers": {
    "bazel": {
      "command": "uvx",
      "args": [
        "bazel-mcp-server",
        "--workspace-root",
        "/path/to/your/bazel/workspace"
      ]
    }
  }
}

Other optional flags:

bazel-mcp-server --bazel-path bazelisk --timeout 600 --max-output-chars 64000

Development

Clone the repo and run tests locally:

git clone https://github.com/saeid-rez/bazel-mcp
cd bazel-mcp
uv sync --group dev
uv run pytest