claude-code-action/docs/configuration.md

Advanced Configuration

Using Custom MCP Configuration

You can add custom MCP (Model Context Protocol) servers to extend Claude's capabilities using the --mcp-config flag in claude_args. These servers merge with the built-in GitHub MCP servers.

Basic Example: Adding a Sequential Thinking Server

- uses: anthropics/claude-code-action@v1
  with:
    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
    claude_args: |
      --mcp-config '{"mcpServers": {"sequential-thinking": {"command": "npx", "args": ["-y", "@modelcontextprotocol/server-sequential-thinking"]}}}'
      --allowedTools mcp__sequential-thinking__sequentialthinking
    # ... other inputs

Passing Secrets to MCP Servers

For MCP servers that require sensitive information like API keys or tokens, you can create a configuration file with GitHub Secrets:

- name: Create MCP Config
  run: |
    cat > /tmp/mcp-config.json << 'EOF'
    {
      "mcpServers": {
        "custom-api-server": {
          "command": "npx",
          "args": ["-y", "@example/api-server"],
          "env": {
            "API_KEY": "${{ secrets.CUSTOM_API_KEY }}",
            "BASE_URL": "https://api.example.com"
          }
        }
      }
    }
    EOF

- uses: anthropics/claude-code-action@v1
  with:
    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
    claude_args: |
      --mcp-config /tmp/mcp-config.json
    # ... other inputs

Using Python MCP Servers with uv

For Python-based MCP servers managed with uv, you need to specify the directory containing your server:

- name: Create MCP Config for Python Server
  run: |
    cat > /tmp/mcp-config.json << 'EOF'
    {
      "mcpServers": {
        "my-python-server": {
          "type": "stdio",
          "command": "uv",
          "args": [
            "--directory",
            "${{ github.workspace }}/path/to/server/",
            "run",
            "server_file.py"
          ]
        }
      }
    }
    EOF

- uses: anthropics/claude-code-action@v1
  with:
    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
    claude_args: |
      --mcp-config /tmp/mcp-config.json
      --allowedTools my-python-server__<tool_name>  # Replace <tool_name> with your server's tool names
    # ... other inputs

For example, if your Python MCP server is at mcp_servers/weather.py, you would use:

"args":
  ["--directory", "${{ github.workspace }}/mcp_servers/", "run", "weather.py"]

Multiple MCP Servers

You can add multiple MCP servers by using multiple --mcp-config flags:

- uses: anthropics/claude-code-action@v1
  with:
    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
    claude_args: |
      --mcp-config /tmp/config1.json
      --mcp-config /tmp/config2.json
      --mcp-config '{"mcpServers": {"inline-server": {"command": "npx", "args": ["@example/server"]}}}'
    # ... other inputs

Important:

• Always use GitHub Secrets (${{ secrets.SECRET_NAME }}) for sensitive values like API keys, tokens, or passwords. Never hardcode secrets directly in the workflow file.
• Your custom servers will override any built-in servers with the same name.
• The claude_args supports multiple --mcp-config flags that will be merged together.

Additional Permissions for CI/CD Integration

The additional_permissions input allows Claude to access GitHub Actions workflow information when you grant the necessary permissions. This is particularly useful for analyzing CI/CD failures and debugging workflow issues.

Enabling GitHub Actions Access

To allow Claude to view workflow run results, job logs, and CI status:

1. Grant the necessary permission to your GitHub token:

   • When using the default GITHUB_TOKEN, add the actions: read permission to your workflow:

   permissions:
     contents: write
     pull-requests: write
     issues: write
     actions: read # Add this line
   

2. Configure the action with additional permissions:

   - uses: anthropics/claude-code-action@v1
     with:
       anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
       additional_permissions: |
         actions: read
       # ... other inputs
   

3. Claude will automatically get access to CI/CD tools: When you enable actions: read, Claude can use the following MCP tools:

   • mcp__github_ci__get_ci_status - View workflow run statuses
   • mcp__github_ci__get_workflow_run_details - Get detailed workflow information
   • mcp__github_ci__download_job_log - Download and analyze job logs

Example: Debugging Failed CI Runs

name: Claude CI Helper
on:
  issue_comment:
    types: [created]

permissions:
  contents: write
  pull-requests: write
  issues: write
  actions: read # Required for CI access

jobs:
  claude-ci-helper:
    runs-on: ubuntu-latest
    steps:
      - uses: anthropics/claude-code-action@v1
        with:
          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
          additional_permissions: |
            actions: read
          # Now Claude can respond to "@claude why did the CI fail?"

Important Notes:

• The GitHub token must have the actions: read permission in your workflow
• If the permission is missing, Claude will warn you and suggest adding it
• Currently, only actions: read is supported, but the format allows for future extensions

Custom Environment Variables

You can pass custom environment variables to Claude Code execution using the settings input. This is useful for CI/test setups that require specific environment variables:

- uses: anthropics/claude-code-action@v1
  with:
    settings: |
      {
        "env": {
          "NODE_ENV": "test",
          "CI": "true",
          "DATABASE_URL": "postgres://test:test@localhost:5432/test_db"
        }
      }
    # ... other inputs

These environment variables will be available to Claude Code during execution, allowing it to run tests, build processes, or other commands that depend on specific environment configurations.

Limiting Conversation Turns

You can limit the number of back-and-forth exchanges Claude can have during task execution using the claude_args input. This is useful for:

• Controlling costs by preventing runaway conversations
• Setting time boundaries for automated workflows
• Ensuring predictable behavior in CI/CD pipelines

- uses: anthropics/claude-code-action@v1
  with:
    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
    claude_args: |
      --max-turns 5  # Limit to 5 conversation turns
    # ... other inputs

When the turn limit is reached, Claude will stop execution gracefully. Choose a value that gives Claude enough turns to complete typical tasks while preventing excessive usage.

Custom Tools

By default, Claude only has access to:

• File operations (reading, committing, editing files, read-only git commands)
• Comment management (creating/updating comments)
• Basic GitHub operations

Claude does not have access to execute arbitrary Bash commands by default. If you want Claude to run specific commands (e.g., npm install, npm test), you must explicitly allow them using the claude_args configuration:

Note: If your repository has a .mcp.json file in the root directory, Claude will automatically detect and use the MCP server tools defined there. However, these tools still need to be explicitly allowed.

- uses: anthropics/claude-code-action@v1
  with:
    claude_args: |
      --allowedTools "Bash(npm install),Bash(npm run test),Edit,Replace,NotebookEditCell"
      --disallowedTools "TaskOutput,KillTask"
    # ... other inputs

Note: The base GitHub tools are always included. Use --allowedTools to add additional tools (including specific Bash commands), and --disallowedTools to prevent specific tools from being used.

Custom Model

Specify a Claude model using claude_args:

- uses: anthropics/claude-code-action@v1
  with:
    claude_args: |
      --model claude-4-0-sonnet-20250805
    # ... other inputs

For provider-specific models:

# AWS Bedrock
- uses: anthropics/claude-code-action@v1
  with:
    use_bedrock: "true"
    claude_args: |
      --model anthropic.claude-4-0-sonnet-20250805-v1:0
    # ... other inputs

# Google Vertex AI
- uses: anthropics/claude-code-action@v1
  with:
    use_vertex: "true"
    claude_args: |
      --model claude-4-0-sonnet@20250805
    # ... other inputs

Claude Code Settings

You can provide Claude Code settings to customize behavior such as model selection, environment variables, permissions, and hooks. Settings can be provided either as a JSON string or a path to a settings file.

Option 1: Settings File

- uses: anthropics/claude-code-action@v1
  with:
    settings: "path/to/settings.json"
    # ... other inputs

Option 2: Inline Settings

- uses: anthropics/claude-code-action@v1
  with:
    settings: |
      {
        "model": "claude-opus-4-1-20250805",
        "env": {
          "DEBUG": "true",
          "API_URL": "https://api.example.com"
        },
        "permissions": {
          "allow": ["Bash", "Read"],
          "deny": ["WebFetch"]
        },
        "hooks": {
          "PreToolUse": [{
            "matcher": "Bash",
            "hooks": [{
              "type": "command",
              "command": "echo Running bash command..."
            }]
          }]
        }
      }
    # ... other inputs

The settings support all Claude Code settings options including:

• model: Override the default model
• env: Environment variables for the session
• permissions: Tool usage permissions
• hooks: Pre/post tool execution hooks
• And more...

For a complete list of available settings and their descriptions, see the Claude Code settings documentation.

Notes:

• The enableAllProjectMcpServers setting is always set to true by this action to ensure MCP servers work correctly.
• The claude_args input provides direct access to Claude Code CLI arguments and takes precedence over settings.
• We recommend using claude_args for simple configurations and settings for complex configurations with hooks and environment variables.

Migration from Deprecated Inputs

Many individual input parameters have been consolidated into claude_args or settings. Here's how to migrate:

Old Input	New Approach
allowed_tools	Use claude_args: "--allowedTools Tool1,Tool2"
disallowed_tools	Use claude_args: "--disallowedTools Tool1,Tool2"
max_turns	Use claude_args: "--max-turns 10"
model	Use claude_args: "--model claude-4-0-sonnet-20250805"
claude_env	Use settings with "env" object
custom_instructions	Use claude_args: "--system-prompt 'Your instructions'"
mcp_config	Use claude_args: "--mcp-config '{...}'"
direct_prompt	Use prompt input instead
override_prompt	Use prompt with GitHub context variables

Custom Executables for Specialized Environments

For specialized environments like Nix, custom container setups, or other package management systems where the default installation doesn't work, you can provide your own executables:

Custom Claude Code Executable

Use path_to_claude_code_executable to provide your own Claude Code binary instead of using the automatically installed version:

- uses: anthropics/claude-code-action@v1
  with:
    path_to_claude_code_executable: "/path/to/custom/claude"
    # ... other inputs

Custom Bun Executable

Use path_to_bun_executable to provide your own Bun runtime instead of the default installation:

- uses: anthropics/claude-code-action@v1
  with:
    path_to_bun_executable: "/path/to/custom/bun"
    # ... other inputs

Important: Using incompatible versions may cause the action to fail. Ensure your custom executables are compatible with the action's requirements.