MORMot

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High-performance Model Context Protocol (MCP) server implementation using the mORMot2 framework.

Implements MCP Specification 2025-06-18 with full support for bidirectional notifications via SSE.

Features

Core

• Pure mORMot2 implementation - No external dependencies beyond mORMot2
• Dual transport support - stdio and HTTP with SSE
• JSON-RPC 2.0 - Full protocol support using TDocVariant
• Modular architecture - Easy to extend with custom tools, resources, and prompts
• Cross-platform - Compiles with Delphi and Free Pascal

MCP Capabilities

• Tools - Register custom tools with JSON Schema validation and listChanged notifications
• Resources - List, read, templates, and subscriptions with URI-based access
• Prompts - List and get with multiple content types (text, image, audio, resource)
• Logging - setLevel method with RFC 5424 log levels
• Completion - Argument auto-completion for prompts and resources

Transport Layer

• stdio transport - JSON-RPC newline-delimited, logs to stderr
• HTTP transport - REST API with Server-Sent Events (SSE), CORS, and TLS support
• Session management - Cryptographic session IDs (128-bit)
• SSE notifications - Real-time bidirectional communication
• Keepalive - Configurable SSE keepalive (default 30s)
• Graceful shutdown - SIGTERM/SIGINT handling with 5s timeout
• Event bus - Thread-safe pub/sub for internal notification routing

Notifications

• notifications/tools/list_changed - Tool registration changes
• notifications/resources/list_changed - Resource changes
• notifications/resources/updated - Subscribed resource updates
• notifications/prompts/list_changed - Prompt changes
• notifications/message - Log messages
• notifications/progress - Progress updates
• notifications/cancelled - Request cancellation

Requirements

• mORMot2 framework
• Delphi 10.3+ (tested) or Free Pascal 3.2+ (not yet tested)

Project Structure

mORMot-MCP-Server/
├── MCPServer.dpr           # Delphi project
├── MCPServer.lpr           # Free Pascal project
├── MCPServer.lpi           # Lazarus project
├── src/
│   ├── Core/
│   │   ├── MCP.Manager.Registry.pas   # Manager registration
│   │   └── MCP.Events.pas             # Event bus (pub/sub)
│   ├── Protocol/
│   │   └── MCP.Types.pas              # Core types and settings
│   ├── Transport/
│   │   ├── MCP.Transport.Base.pas     # Transport abstraction
│   │   ├── MCP.Transport.Stdio.pas    # stdio transport
│   │   └── MCP.Transport.Http.pas     # HTTP + SSE transport
│   ├── Server/
│   │   └── MCP.Server.pas             # Legacy HTTP server
│   ├── Managers/
│   │   ├── MCP.Manager.Core.pas       # initialize, ping
│   │   ├── MCP.Manager.Tools.pas      # tools/list, tools/call
│   │   ├── MCP.Manager.Resources.pas  # resources/*, subscriptions
│   │   ├── MCP.Manager.Prompts.pas    # prompts/list, prompts/get
│   │   ├── MCP.Manager.Logging.pas    # logging/setLevel
│   │   └── MCP.Manager.Completion.pas # completion/complete
│   ├── Tools/
│   │   ├── MCP.Tool.Base.pas          # Base tool class
│   │   ├── MCP.Tool.Echo.pas          # Echo example
│   │   └── MCP.Tool.GetTime.pas       # GetTime example
│   ├── Resources/
│   │   └── MCP.Resource.Base.pas      # Base resource class
│   └── Prompts/
│       └── MCP.Prompt.Base.pas        # Base prompt class

Building

With Delphi

Open MCPServer.dproj in Delphi IDE. Ensure mORMot2 source paths are configured.

# Or from command line
msbuild MCPServer.dproj /p:Config=Release /p:Platform=Win64

With Free Pascal / Lazarus

lazbuild MCPServer.lpi

Usage

stdio Transport (for Claude Desktop)

MCPServer.exe --transport=stdio

Configure in Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "mormot-server": {
      "command": "C:\\path\\to\\MCPServer.exe",
      "args": ["--transport=stdio"]
    }
  }
}

HTTP Transport (for web clients)

# Default port 3000
MCPServer.exe --transport=http

# Custom port
MCPServer.exe --transport=http --port=8080

HTTPS / TLS

# Self-signed certificate (development/testing)
MCPServer.exe --transport=http --tls-self-signed

# With certificate files
MCPServer.exe --transport=http --tls --cert=server.crt --key=server.key

# With encrypted private key
MCPServer.exe --transport=http --tls --cert=server.crt --key=server.key --key-password=secret

TLS uses mORMot2's native support: SChannel on Windows (no extra DLLs), OpenSSL on Linux.

SSE Connection

# Open SSE stream for notifications
curl -N -H "Accept: text/event-stream" http://localhost:3000/mcp

API Examples

Initialize Session

curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -H "Mcp-Protocol-Version: 2025-06-18" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2025-06-18",
      "capabilities": {},
      "clientInfo": {"name": "test", "version": "1.0"}
    }
  }'

List Tools

curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -H "Mcp-Session-Id: <session-id>" \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/list"}'

Call Tool

curl -X POST http://localhost:3000/mcp \
  -H "Content-Type: application/json" \
  -H "Mcp-Session-Id: <session-id>" \
  -d '{
    "jsonrpc": "2.0",
    "id": 3,
    "method": "tools/call",
    "params": {
      "name": "echo",
      "arguments": {"message": "Hello, World!"}
    }
  }'

Adding Custom Tools

unit MCP.Tool.MyTool;

{$I mormot.defines.inc}

interface

uses
  mormot.core.base,
  mormot.core.variants,
  MCP.Tool.Base;

type
  TMCPToolMyTool = class(TMCPToolBase)
  protected
    function BuildInputSchema: Variant; override;
  public
    constructor Create; override;
    function Execute(const Arguments: Variant): Variant; override;
  end;

implementation

constructor TMCPToolMyTool.Create;
begin
  inherited;
  fName := 'my_tool';
  fDescription := 'My custom tool';
end;

function TMCPToolMyTool.BuildInputSchema: Variant;
begin
  TDocVariantData(Result).InitFast;
  TDocVariantData(Result).S['type'] := 'object';
  // Add properties...
end;

function TMCPToolMyTool.Execute(const Arguments: Variant): Variant;
begin
  // Return success
  Result := ToolResultText('Done!');

  // Or return error
  // Result := ToolResultText('Error message', True);
end;

end.

Register in MCPServer.dpr:

ToolsManager.RegisterTool(TMCPToolMyTool.Create);

Configuration

Settings in MCP.Types.pas:

Settings.ServerName := 'mORMot-MCP-Server';
Settings.ServerVersion := '1.0.0';
Settings.Port := 3000;
Settings.Host := '0.0.0.0';
Settings.Endpoint := '/mcp';
Settings.SSEKeepaliveIntervalMs := 30000;  // 30 seconds

Performance

Aspect	mORMot2 MCP Server
HTTP Server	THttpAsyncServer (async I/O)
JSON	TDocVariant (zero-copy)
Memory	Minimal allocation
Threading	Thread pool
SSE	Native implementation

License

MIT License - See LICENSE file.

See Also

• mORMot2 Documentation
• MCP Specification
• MCP Protocol Version 2025-06-18