colinrozzi/component-tools-mcp

Component Tools MCP Server

A Model Context Protocol (MCP) server that provides tools for WebAssembly component development using cargo component.

Features

This MCP server exposes two main tools for working with WebAssembly components:

Tools Available

1. component-bindings - Generates bindings for WebAssembly components

   • Runs cargo component bindings in the specified directory
   • Supports additional arguments

2. component-build - Builds WebAssembly components

   • Runs cargo component build in the specified directory
   • Supports additional arguments like --release, --target, etc.

Prerequisites

Before using this server, you need to have cargo-component installed:

cargo install cargo-component

Installation

1. Clone this repository and navigate to the component-tools-mcp directory
2. Build the server:

cargo build --release

Usage

Running the Server

# Run with default settings (allows access to all directories)
cargo run

# Run with restricted directory access
cargo run -- --allowed-dir /path/to/your/components --allowed-dir /another/path

# Run with custom logging
cargo run -- --log-level debug --log-file component-tools.log

Command Line Options

• --allowed-dir <DIR>: Specify directories where component operations are allowed (can be used multiple times)
• --log-level <LEVEL>: Set log level (trace, debug, info, warn, error) - defaults to "info"
• --log-file <FILE>: Log to file instead of stderr

Using with MCP Clients

Once the server is running, MCP clients can use the following tools:

component-bindings

Generate bindings for a component project:

{
  "name": "component-bindings",
  "arguments": {
    "directory": "/path/to/your/component/project",
    "args": ["--out-dir", "generated"]
  }
}

component-build

Build a component project:

{
  "name": "component-build", 
  "arguments": {
    "directory": "/path/to/your/component/project",
    "args": ["--release"]
  }
}

Security Features

• Directory Restrictions: When --allowed-dir is specified, the server will only operate within those directories
• Path Validation: All paths are validated before execution
• Command Isolation: Only cargo component commands are executed

Error Handling

The server provides detailed error information including:

• Command execution status
• stdout and stderr output
• Exit codes
• Path validation errors

Development

Building

cargo build

Testing

cargo test

Running in Development

cargo run -- --log-level debug

Example Usage

Basic Usage

1. Start the server:

cargo run

2. Start with directory restrictions:

cargo run -- --allowed-dir /home/user/components --allowed-dir /home/user/other-components

3. Start with debug logging:

cargo run -- --log-level debug --log-file component-tools.log

Using with MCP Clients

The server exposes two tools that can be called by MCP clients:

component-bindings

{
  "name": "component-bindings",
  "arguments": {
    "directory": "/path/to/your/component/project",
    "args": ["--out-dir", "generated"]
  }
}

component-build

{
  "name": "component-build", 
  "arguments": {
    "directory": "/path/to/your/component/project",
    "args": ["--release"]
  }
}

Example MCP Client Configuration

For Claude Desktop or other MCP clients, add this to your configuration:

{
  "mcpServers": {
    "component-tools": {
      "command": "cargo",
      "args": ["run", "--release"],
      "cwd": "/path/to/component-tools-mcp",
      "env": {
        "RUST_LOG": "info"
      }
    }
  }
}

Integration with Other Tools

This MCP server is designed to work with:

• Claude desktop app
• Other MCP-compatible clients
• Development workflows involving WebAssembly components

Troubleshooting

"cargo-component not found" Error

Make sure you have cargo-component installed:

cargo install cargo-component

Permission Errors

If you're getting permission errors:

1. Check that the target directory exists and is writable
2. Ensure the directory is in your allowed directories list (if using --allowed-dir)

Build Failures

Component build failures will be reported with full stdout/stderr output to help with debugging.