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Crush supports the Model Context Protocol (MCP), which allows you to extend Crush’s capabilities with custom tools, resources, and prompts provided by external servers. MCP servers can provide:
  • Tools - Additional commands Crush can execute
  • Resources - External data sources Crush can read
  • Prompts - Reusable prompt templates

​
Transport Types

Crush supports three MCP transport types:
  • stdio - Command-line servers that communicate over stdin/stdout
  • http - HTTP endpoints that implement the MCP protocol
  • sse - Server-Sent Events for streaming MCP responses

​
Configuration

Configure MCP servers in your crush.json file: 
{
  "$schema": "https://charm.land/crush.json",
  "mcp": {
    "filesystem": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/mcp-server.js"],
      "timeout": 120,
      "disabled": false,
      "disabled_tools": ["some-tool-name"],
      "env": {
        "NODE_ENV": "production"
      }
    },
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "timeout": 120,
      "disabled": false,
      "disabled_tools": ["create_issue", "create_pull_request"],
      "headers": {
        "Authorization": "Bearer $GH_PAT"
      }
    },
    "streaming-service": {
      "type": "sse",
      "url": "https://example.com/mcp/sse",
      "timeout": 120,
      "disabled": false,
      "headers": {
        "API-Key": "$(echo $API_KEY)"
      }
    }
  }
}

​
Configuration Options

​
type

Type: string (required)
Values: stdio, http, sse
Default: stdio The transport type for the MCP server. 
{
  "mcp": {
    "my-server": {
      "type": "stdio"
    }
  }
}

​
stdio Transport Options

For stdio servers:

​
command

Type: string The executable command for the MCP server. 
{
  "mcp": {
    "filesystem": {
      "type": "stdio",
      "command": "node"
    }
  }
}

​
args

Type: string[] Command-line arguments to pass to the MCP server. 
{
  "mcp": {
    "filesystem": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/mcp-server.js", "--verbose"]
    }
  }
}

​
env

Type: object Environment variables to set for the MCP server process. 
{
  "mcp": {
    "filesystem": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/mcp-server.js"],
      "env": {
        "NODE_ENV": "production",
        "LOG_LEVEL": "info"
      }
    }
  }
}

​
http and sse Transport Options

For http and sse servers:

​
url

Type: string (required for http/sse) The URL endpoint for the MCP server. 
{
  "mcp": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/"
    }
  }
}

​
headers

Type: object HTTP headers to send with requests. 
{
  "mcp": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer $GH_PAT",
        "Content-Type": "application/json"
      }
    }
  }
}

​
Common Options

These options apply to all transport types:

​
disabled

Type: boolean
Default: false Disable this MCP server without removing its configuration. 
{
  "mcp": {
    "filesystem": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/mcp-server.js"],
      "disabled": true
    }
  }
}

​
disabled_tools

Type: string[] List of specific tools from this MCP server to disable. 
{
  "mcp": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "disabled_tools": [
        "create_issue",
        "create_pull_request",
        "delete_repository"
      ]
    }
  }
}
Use disabled_tools to prevent Crush from accessing dangerous or unwanted tools while still using the MCP server’s other capabilities.

​
timeout

Type: integer
Default: 15 Timeout in seconds for MCP server connections. 
{
  "mcp": {
    "slow-server": {
      "type": "http",
      "url": "https://example.com/mcp",
      "timeout": 120
    }
  }
}

​
Environment Variable Expansion

MCP configurations support environment variable expansion using $VAR or $(echo $VAR) syntax: 
{
  "mcp": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer $GH_PAT"
      }
    },
    "custom-service": {
      "type": "sse",
      "url": "https://example.com/mcp/sse",
      "headers": {
        "API-Key": "$(echo $API_KEY)"
      }
    }
  }
}

​
Example Configurations

​
stdio: Node.js MCP Server

{
  "mcp": {
    "filesystem": {
      "type": "stdio",
      "command": "node",
      "args": ["/Users/me/.config/mcp/filesystem-server.js"],
      "env": {
        "NODE_ENV": "production",
        "ALLOWED_PATHS": "/home,/tmp"
      }
    }
  }
}

​
stdio: Python MCP Server

{
  "mcp": {
    "database": {
      "type": "stdio",
      "command": "python",
      "args": ["-m", "mcp_server.database"],
      "env": {
        "DB_CONNECTION": "$DATABASE_URL"
      },
      "timeout": 30
    }
  }
}

​
http: REST API MCP Server

{
  "mcp": {
    "api-gateway": {
      "type": "http",
      "url": "https://api.example.com/mcp/v1",
      "headers": {
        "Authorization": "Bearer $API_TOKEN",
        "X-API-Version": "2024-01"
      },
      "timeout": 60
    }
  }
}

​
sse: Streaming MCP Server

{
  "mcp": {
    "realtime-data": {
      "type": "sse",
      "url": "https://stream.example.com/mcp",
      "headers": {
        "Authorization": "$(echo $STREAM_TOKEN)"
      },
      "timeout": 300
    }
  }
}

​
Disabling Specific Tools

You can disable specific tools while keeping the MCP server active: 
{
  "mcp": {
    "github": {
      "type": "http",
      "url": "https://api.githubcopilot.com/mcp/",
      "headers": {
        "Authorization": "Bearer $GH_PAT"
      },
      "disabled_tools": [
        "delete_repository",
        "force_push",
        "delete_branch"
      ]
    }
  }
}
Use disabled_tools to implement least-privilege access - only enable the tools you actually need.

​
MCP Resources

MCP servers can provide resources that Crush can read. Use the built-in MCP resource tools:
  • list_mcp_resources - List available resources from MCP servers
  • read_mcp_resource - Read a specific MCP resource
These tools are automatically available when MCP servers are configured.

​
Debugging MCP Issues

Enable debug logging to troubleshoot MCP server issues: 
{
  "options": {
    "debug": true
  }
}
Or use the command-line flag: 
crush --debug
Logs are written to ./.crush/logs/crush.log in your project directory.

​
Finding MCP Servers

Explore available MCP servers:

​
Next Steps

Skills

Configure Agent Skills for reusable capabilities

Permissions

Control tool and MCP permissions

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