Mcpx Rust

A Rust implementation of mcpx, a CLI utility that transforms Model Context Protocol (MCP) servers into composable command-line tools.

Features

• Server Discovery: List all configured MCP servers.
• Tool Discovery: List available tools for a specific server.
• Dynamic Invocation: Map MCP tool schemas to CLI arguments.
• JSON Output: Optional JSON output for piping into tools like jq.
• Configuration: Simple TOML-based configuration.

Installation

cargo install mcpx-rust

Configuration

mcpx-rust reads server definitions from ~/.config/mcpx/config.toml.

Example config.toml:

[mcp_servers.everything]
command = "npx"
args = ["-y", "@modelcontextprotocol/server-everything"]

[mcp_servers.github]
command = "npx"
args = ["-y", "@modelcontextprotocol/server-github"]
env = { GITHUB_PERSONAL_ACCESS_TOKEN = "your_token_here" }

You can also use the MCPX_CONFIG environment variable to point to a different configuration file.

Usage

Usage: mcpx-rust [OPTIONS] [SERVER] [TOOL] [ARGS]... [COMMAND]

To list tools for a server, use: mcpx-rust <SERVER>

List configured servers

mcpx-rust list

List tools for a server (Discovery)

mcpx-rust <server_name>
# OR
mcpx-rust <server_name> --help

Call a tool

mcpx-rust <server_name> <tool_name> [args...]

mcpx-rust supports multiple argument formats and automatically normalizes them based on the server's JSON Schema:

• GNU-style flags: --key value or --flag
• Key-Value pairs: key=value
• Positional arguments: Passed to the tool as a list (useful for servers that handle unstructured input or for extra validation).
• Schema-Aware Coercion: Values are automatically converted to JSON primitives (booleans, numbers) based on the server's schema. If no schema is available, the tool is conservative and defaults to strings for ambiguous identifiers like "1.1" while still supporting explicit JSON objects and arrays.
• Flat Server Support: Automatically detects servers that expect a flat list of arguments (like args: ["key=value"]) and maps your flags accordingly.

Example:

# Using flags
mcpx-rust spec sc_init --name iot-hub --recursive

# Using key=value pairs
mcpx-rust everything echo message="Hello from Rust"

To improve performance, mcpx-rust caches tool schemas locally in ~/.cache/mcpx-rust/.

JSON output

mcpx-rust everything echo message="Hello" --json

License

MIT