llm-agent-backend/app/mcp_tools.py

from pydantic import BaseModel, Field, create_model
from langchain_core.tools import StructuredTool

# ----------------- MCP MANAGER -----------------
try:
    from mcp.client.stdio import stdio_client, StdioServerParameters
    from mcp.client.session import ClientSession
    MCP_AVAILABLE = True
except ImportError:
    MCP_AVAILABLE = False

_MCP_CACHED_TOOLS = {}

def json_schema_to_pydantic(schema: dict, model_name: str) -> type[BaseModel]:
    """Преобразует JSON Schema от MCP сервера в Pydantic модель для LangChain"""
    fields = {}
    properties = schema.get("properties", {})
    required = schema.get("required", [])

    for key, val in properties.items():
        t = val.get("type", "string")
        py_type = str
        if t == "integer": py_type = int
        elif t == "number": py_type = float
        elif t == "boolean": py_type = bool
        elif t == "array": py_type = list
        elif t == "object": py_type = dict

        desc = val.get("description", "")
        if key in required:
            fields[key] = (py_type, Field(..., description=desc))
        else:
            fields[key] = (py_type, Field(default=None, description=desc))

    if not fields:
        fields["kwargs"] = (dict, Field(default_factory=dict, description="Аргументы"))

    return create_model(model_name, **fields)

def create_mcp_tool(server_config, tool_name, tool_desc, json_schema, full_env, args, debug_callback=None):
    """Обертка, которая поднимает контейнер/процесс ровно на 1 вызов тула и убивает его"""
    args_schema = json_schema_to_pydantic(json_schema, f"MCP_{tool_name.replace('-','_')}_Schema")
    command = server_config.get("command")

    def mcp_tool_runner(**kwargs):
        import asyncio
        import json
        input_json = json.dumps(kwargs, indent=2, ensure_ascii=False)

        async def _run():
            server_params = StdioServerParameters(command=command, args=args, env=full_env)
            async with stdio_client(server_params) as (read, write):
                async with ClientSession(read, write) as session:
                    await session.initialize()
                    result = await session.call_tool(tool_name, arguments=kwargs)
                    text_outputs = []
                    for c in result.content:
                        if hasattr(c, 'text'):
                            text_outputs.append(c.text)
                        else:
                            text_outputs.append(str(c))
                    return "\n".join(text_outputs)

        raw_output = asyncio.run(_run())

        if debug_callback:
            # debug_callback(f"MCP: {tool_name}\n" + input_json, raw_output)
            debug_callback(kwargs, raw_output) 

        return f"Инструмент '{tool_name}' вернул следующий результат:\n<tool_output>\n{raw_output}\n</tool_output>"

    return StructuredTool.from_function(
        func=mcp_tool_runner,
        name=tool_name.replace('-','_'), # Langchain не любит тире в именах
        description=tool_desc or f"MCP Tool {tool_name}",
        args_schema=args_schema
    )

def fetch_mcp_tools(server_config, debug_callback=None):
    """Один раз читает список тулов от сервера и кеширует их схемы"""
    if not MCP_AVAILABLE:
        print("⚠️ MCP серверы настроены, но библиотека 'mcp' не установлена. Выполните: pip install mcp")
        return []

    import asyncio
    import shlex
    import os

    config_hash = str(server_config) # primitive hash
    if config_hash in _MCP_CACHED_TOOLS:
        return _MCP_CACHED_TOOLS[config_hash]

    async def _fetch():
        command = server_config.get("command", "")
        args_str = server_config.get("args", "")
        args = shlex.split(args_str) if args_str else []

        env_dict = {}
        env_str = server_config.get("envString", "")
        if env_str:
            for pair in env_str.split(','):
                if '=' in pair:
                    k, v = pair.split('=', 1)
                    env_dict[k.strip()] = v.strip()

        full_env = {**os.environ.copy(), **env_dict}
        server_params = StdioServerParameters(command=command, args=args, env=full_env)

        async with stdio_client(server_params) as (read, write):
            async with ClientSession(read, write) as session:
                await session.initialize()
                tools_resp = await session.list_tools()
                return tools_resp.tools, full_env, args

    try:
        raw_tools, full_env, args = asyncio.run(_fetch())
        wrapped_tools = []
        
        # Получаем кастомные описания из конфига
        fetched_tools_ui = server_config.get("fetchedTools", [])
        custom_descriptions = {t.get("name"): t.get("customDescription") for t in fetched_tools_ui}

        for t in raw_tools:
            # Если есть кастомное описание и оно не пустое - используем его
            c_desc = custom_descriptions.get(t.name)
            final_description = c_desc if c_desc and c_desc.strip() else t.description
            
            wrapped_tools.append(create_mcp_tool(server_config, t.name, final_description, t.inputSchema, full_env, args, debug_callback))
            
        _MCP_CACHED_TOOLS[config_hash] = wrapped_tools
        print(f"🔌 Успешно загружено {len(wrapped_tools)} инструментов от MCP-сервера '{server_config.get('name')}'")
        return wrapped_tools
    except Exception as e:
        print(f"❌ Ошибка инициализации MCP сервера {server_config.get('name')}: {e}")
        return []

def get_raw_mcp_tools_list(server_config):
    """Метод для UI: просто возвращает список доступных инструментов в JSON-friendly формате"""
    if not MCP_AVAILABLE:
        return []

    import asyncio
    import shlex
    import os

    async def _fetch_raw():
        command = server_config.get("command", "")
        args_str = server_config.get("args", "")
        args = shlex.split(args_str) if args_str else []

        env_dict = {}
        env_str = server_config.get("envString", "")
        if env_str:
            for pair in env_str.split(','):
                if '=' in pair:
                    k, v = pair.split('=', 1)
                    env_dict[k.strip()] = v.strip()

        full_env = {**os.environ.copy(), **env_dict}
        server_params = StdioServerParameters(command=command, args=args, env=full_env)

        async with stdio_client(server_params) as (read, write):
            async with ClientSession(read, write) as session:
                await session.initialize()
                tools_resp = await session.list_tools()
                return tools_resp.tools

    try:
        raw_tools = asyncio.run(_fetch_raw())
        return [{"name": t.name, "description": t.description} for t in raw_tools]
    except Exception as e:
        print(f"Ошибка получения списка тулов: {e}")
        return []