Composable MCP

What it does

Composable MCP is a Model Context Protocol server that enables AI agents to use WebAssembly (Wasm) Components as tools. It allows for a highly modular architecture where domain-specific tools can be developed as standalone Wasm components and composed together with specific host capabilities.

Tools

• Dynamic Tool Discovery: Automatically exposes top-level Wasm components as MCP tools.
• Component Selection: Allows filtering which components are exposed using selectors (e.g., matching by metadata or name).
• Capability Management: Manages host runtime capabilities (like HTTP or WASI) for guest components via TOML configuration.

Installation

Install the toolbelt via cargo:

cargo install --path .

Then run the server specifying your .wasm files or a .toml configuration:

toolbelt hello.wasm calculator.wasm

For Claude Desktop, use the following configuration in claude_desktop_config.json:

{
  "mcpServers": {
    "composable-mcp": {
      "command": "toolbelt",
      "args": ["path/to/your/components.toml"]
    }
  }
}

Supported hosts

• Claude