Nim Model Context Protocol (MCP) SDK

Nim implementation of the Model Context Protocol (MCP) for building AI agent capabilities.

Installation

1. Install Nim compiler
2. Clone repository:

git clone https://github.com/yourusername/mcp-nim.git
cd mcp-nim

Configuration

Claude Integration

1. Locate MCP config file:

   • Claude Desktop: ~/Library/Application Support/Claude/claude_desktop_config.json (macOS)
   • Claude Desktop: C:\Users\xxx\AppData\Roaming\Claude\claude_desktop_config.json (Windows)
   • Cursor: %APPDATA%\Cursor\User\globalStorage\rooveterinaryinc.roo-cline\settings\cline_mcp_settings.json (Windows)

2. Add server configuration:

{
  "mcpServers": {
    "filesystem-server": {
      "command": "nim",
      "args": ["c","-r", "examples/filesystem_server.nim"],
      "cwd": "/path/to/sdk/root",
      "disabled": false
    }
  }
}

Development

Creating MCP Servers

import std/[asyncdispatch, json, options]
import ../src/mcp/[client, types]
import ../src/mcp/shared/[protocol, stdio, transport]

proc main() {.async.} =
  let transport = newStdioTransport()
  let protocol = newProtocol(some(ProtocolOptions()))
  
  protocol.setRequestHandler(Request, proc(
    request: Request,
    extra: RequestHandlerExtra
  ): Future[McpResult] {.async.} =
    if request.`method` == "your-method":
      result = McpResult()
    else:
      raise newMcpError(ErrorCode.MethodNotFound)
  )

  await protocol.connect(transport)
  await sleepAsync(1000)
  await protocol.close()

when isMainModule:
  waitFor main()

Examples

Filesystem Server

protocol.setRequestHandler("tools/list", proc(request: base_types.JsonRpcRequest, extra: protocol.RequestHandlerExtra): Future[JsonNode] {.async.} =
  result = %*{
    "tools": [
      {
        "name": "read_file",
        "description": "Read file contents",
        "inputSchema": {
          "type": "object",
          "properties": {
            "path": {"type": "string"}
          },
          "required": ["path"],
          "additionalProperties": false
        }
      }
    ]
  }
)

Features

• Type-safe RPC communication
• JSON serialization/deserialization
• Async I/O with progress notifications
• Capability-based security model
• Thread-safe implementations

Building

nimble build
nimble test
nimble docs

License

MIT License