neuron-mcp

Model Context Protocol (MCP) integration for the neuron agent blocks ecosystem. Wraps the official Rust MCP SDK (rmcp) and bridges MCP tools, resources, and prompts into neuron's type system. Provides both client and server functionality.

Installation

cargo add neuron-mcp

Key Types

McpClient -- connects to MCP servers via stdio (connect_stdio) or Streamable HTTP (connect_http). Provides methods for listing and calling tools, reading resources, and fetching prompts.
McpToolBridge -- bridges a single MCP tool to the ToolDyn trait so it can be registered in a ToolRegistry and used alongside native tools.
McpServer -- exposes a ToolRegistry as an MCP server, handling tools/list and tools/call requests.
StdioConfig / HttpConfig -- connection configuration structs.
PaginatedList<T> -- paginated response wrapper with items and next_cursor.
McpResource, McpResourceContents, McpPrompt -- MCP resource and prompt types.

Features

Full MCP client: tools, resources, prompts, pagination.
Full MCP server: expose any ToolRegistry over stdio.
Automatic tool discovery via McpToolBridge::discover or McpClient::discover_tools.
Supports both stdio (child process) and Streamable HTTP transports.
Error types convert cleanly from rmcp::ServiceError to McpError.

Usage

use std::sync::Arc;
use neuron_mcp::{McpClient, McpToolBridge, StdioConfig};
use neuron_tool::ToolRegistry;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Connect to an MCP server via stdio
    let client = Arc::new(McpClient::connect_stdio(StdioConfig {
        command: "npx".to_string(),
        args: vec![
            "-y".to_string(),
            "@modelcontextprotocol/server-everything".to_string(),
        ],
        env: vec![],
    }).await?);

    // Discover all tools and get them as ToolDyn trait objects
    let tools = McpToolBridge::discover(&client).await?;

    // Register discovered tools into a ToolRegistry
    let mut registry = ToolRegistry::new();
    for tool in tools {
        registry.register_dyn(tool);
    }

    // List registered tool names
    for def in registry.definitions() {
        println!("tool: {}", def.name);
    }
    Ok(())
}

Exposing tools as an MCP server

You can also expose any ToolRegistry as an MCP server, so external MCP clients can call your tools:

use neuron_tool::ToolRegistry;
use neuron_mcp::McpServer;

let mut registry = ToolRegistry::new();
registry.register(MyTool);

let server = McpServer::new(registry)
    .with_name("my-agent-tools")
    .with_instructions("Tools for interacting with the codebase.");

// Blocks until the client disconnects
server.serve_stdio().await?;

Part of neuron

This crate is one block in the neuron composable agent toolkit. It depends on neuron-types, neuron-tool, and rmcp.

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.

neuron-mcp 0.3.0