第26章 MCP与其他技术栈的结合

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第26章 MCP与其他技术栈的结合

前言

本章是第四部分的收官之作。我们将探讨如何将MCP与Agent系统、检索增强生成(RAG)、模型微调、工作流编排、多模态处理等前沿技术栈相结合,构建更加智能、灵活、强大的AI系统。


26.1 MCP + Agent:自主决策系统

26.1.1 Agent-MCP架构

graph TB
    A["用户意图"] --> B["Agent决策引擎"]
    B --> C["感知模块"]
    B --> D["规划模块"]
    B --> E["执行模块"]
    
    C --> C1["MCP工具"]
    C --> C2["环境感知"]
    
    D --> D1["任务规划"]
    D --> D2["资源分配"]
    
    E --> E1["MCP执行"]
    E --> E2["反馈收集"]
    
    E2 --> B
    E1 --> F["执行结果"]

26.1.2 Agent-MCP实现

from typing import Dict, List, Optional, Any
from dataclasses import dataclass
from datetime import datetime
from enum import Enum

class AgentState(Enum):
    """Agent状态"""
    IDLE = "idle"
    THINKING = "thinking"
    ACTING = "acting"
    OBSERVING = "observing"
    DONE = "done"


@dataclass
class Action:
    """动作"""
    tool: str
    params: Dict[str, Any]
    reason: str


class ReActAgent:
    """ReAct Agent(Reasoning + Acting)"""
    
    def __init__(self, mcp_client, model_client):
        """
        初始化Agent
        
        Args:
            mcp_client: MCP客户端
            model_client: 模型客户端
        """
        self.mcp_client = mcp_client
        self.model = model_client
        self.state = AgentState.IDLE
        self.history = []
        self.max_steps = 10
    
    async def think(self, observation: str) -> str:
        """
        思考
        
        Args:
            observation: 观察结果
            
        Returns:
            思考内容
        """
        prompt = f"""
        根据观察结果进行推理:
        观察:{observation}
        
        请分析现状并制定下一步行动。
        """
        
        response = await self.model.generate(prompt)
        return response
    
    async def plan_action(self, thought: str) -> Optional[Action]:
        """
        规划动作
        
        Args:
            thought: 思考内容
            
        Returns:
            动作
        """
        # 从思考内容中解析动作
        action_prompt = f"""
        基于以下思考,确定要执行的工具:
        {thought}
        
        返回JSON格式:{{"tool": "...", "params": {{...}}, "reason": "..."}}
        """
        
        response = await self.model.generate(action_prompt)
        
        try:
            import json
            action_data = json.loads(response)
            return Action(
                tool=action_data["tool"],
                params=action_data["params"],
                reason=action_data["reason"]
            )
        except:
            return None
    
    async def act(self, action: Action) -> Dict[str, Any]:
        """
        执行动作
        
        Args:
            action: 动作
            
        Returns:
            执行结果
        """
        self.state = AgentState.ACTING
        
        try:
            result = await self.mcp_client.call_tool(
                action.tool,
                action.params
            )
            
            return {
                "status": "success",
                "tool": action.tool,
                "result": result,
                "reason": action.reason
            }
        
        except Exception as e:
            return {
                "status": "error",
                "tool": action.tool,
                "error": str(e),
                "reason": action.reason
            }
    
    async def run(self, goal: str) -> Dict[str, Any]:
        """
        运行Agent
        
        Args:
            goal: 目标
            
        Returns:
            执行结果
        """
        self.state = AgentState.THINKING
        observation = f"任务:{goal}"
        
        for step in range(self.max_steps):
            # 思考
            thought = await self.think(observation)
            self.history.append({"type": "thought", "content": thought})
            
            # 规划动作
            action = await self.plan_action(thought)
            if not action:
                break
            
            self.history.append({
                "type": "action",
                "content": action.reason,
                "tool": action.tool
            })
            
            # 执行动作
            result = await self.act(action)
            self.history.append({"type": "observation", "content": result})
            
            # 检查是否完成
            if result["status"] == "error" or step == self.max_steps - 1:
                break
            
            observation = str(result)
        
        self.state = AgentState.DONE
        
        return {
            "goal": goal,
            "steps": len(self.history),
            "status": "completed",
            "history": self.history
        }

26.2 MCP + RAG:检索增强生成

26.2.1 RAG-MCP集成

class VectorStore:
    """向量存储"""
    
    def __init__(self):
        self.embeddings: Dict[str, List[float]] = {}
        self.documents: Dict[str, str] = {}
    
    def add_document(self, doc_id: str, content: str,
                    embedding: List[float]):
        """添加文档"""
        self.documents[doc_id] = content
        self.embeddings[doc_id] = embedding
    
    def search(self, query_embedding: List[float],
              top_k: int = 5) -> List[tuple]:
        """
        向量搜索
        
        Args:
            query_embedding: 查询向量
            top_k: 返回数量
            
        Returns:
            相关文档列表
        """
        import math
        
        scores = []
        for doc_id, embedding in self.embeddings.items():
            # 计算余弦相似度
            dot_product = sum(a * b for a, b in zip(query_embedding, embedding))
            magnitude1 = math.sqrt(sum(a * a for a in query_embedding))
            magnitude2 = math.sqrt(sum(a * a for a in embedding))
            
            if magnitude1 > 0 and magnitude2 > 0:
                similarity = dot_product / (magnitude1 * magnitude2)
                scores.append((doc_id, similarity, self.documents[doc_id]))
        
        # 按相似度排序
        scores.sort(key=lambda x: x[1], reverse=True)
        return scores[:top_k]


class RAGSystem:
    """RAG系统"""
    
    def __init__(self, mcp_client, model_client):
        """
        初始化RAG系统
        
        Args:
            mcp_client: MCP客户端
            model_client: 模型客户端
        """
        self.mcp_client = mcp_client
        self.model = model_client
        self.vector_store = VectorStore()
    
    async def retrieve(self, query: str) -> List[str]:
        """
        检索相关文档
        
        Args:
            query: 查询
            
        Returns:
            相关文档
        """
        # 获取查询向量
        query_embedding = await self.model.embed(query)
        
        # 搜索
        results = self.vector_store.search(query_embedding, top_k=5)
        
        return [doc for _, _, doc in results]
    
    async def augment_and_generate(self, query: str) -> str:
        """
        增强检索和生成
        
        Args:
            query: 查询
            
        Returns:
            生成结果
        """
        # 检索相关文档
        documents = await self.retrieve(query)
        
        # 构建增强提示
        context = "\n".join(documents)
        augmented_prompt = f"""
        基于以下文档上下文回答问题:
        
        上下文:
        {context}
        
        问题:{query}
        
        请基于上下文提供详细答案。
        """
        
        # 生成
        response = await self.model.generate(augmented_prompt)
        return response
    
    async def retrieve_from_mcp(self, query: str) -> List[str]:
        """
        从MCP源检索
        
        Args:
            query: 查询
            
        Returns:
            检索结果
        """
        result = await self.mcp_client.call_tool(
            "search_documents",
            {"query": query}
        )
        
        return result.get("documents", [])

26.3 MCP + 微调:性能优化

26.3.1 微调工作流

class FineTuningPipeline:
    """微调管道"""
    
    def __init__(self, mcp_client, model_client):
        """
        初始化微调管道
        
        Args:
            mcp_client: MCP客户端
            model_client: 模型客户端
        """
        self.mcp_client = mcp_client
        self.model = model_client
        self.training_data = []
        self.metrics = {}
    
    async def collect_training_data(self) -> List[Dict]:
        """
        从MCP收集训练数据
        
        Returns:
            训练数据
        """
        # 从MCP工具获取数据
        data = await self.mcp_client.call_tool(
            "get_training_data",
            {"limit": 1000}
        )
        
        return data.get("samples", [])
    
    async def prepare_dataset(self, raw_data: List[Dict]) -> List[Dict]:
        """
        准备数据集
        
        Args:
            raw_data: 原始数据
            
        Returns:
            处理后的数据
        """
        prepared = []
        
        for sample in raw_data:
            prepared.append({
                "instruction": sample.get("instruction"),
                "input": sample.get("input", ""),
                "output": sample.get("output"),
                "category": sample.get("category", "general")
            })
        
        return prepared
    
    async def fine_tune(self, dataset: List[Dict]) -> Dict:
        """
        执行微调
        
        Args:
            dataset: 数据集
            
        Returns:
            微调结果
        """
        from datetime import datetime
        
        start_time = datetime.now()
        
        # 微调配置
        config = {
            "model": "base_model",
            "epochs": 3,
            "batch_size": 32,
            "learning_rate": 1e-4,
            "dataset_size": len(dataset)
        }
        
        # 模拟微调过程
        result = {
            "status": "completed",
            "config": config,
            "training_time_seconds": (datetime.now() - start_time).total_seconds(),
            "metrics": {
                "final_loss": 0.15,
                "accuracy": 0.92,
                "f1_score": 0.89
            }
        }
        
        return result
    
    async def evaluate(self, model_path: str) -> Dict:
        """
        评估模型
        
        Args:
            model_path: 模型路径
            
        Returns:
            评估结果
        """
        # 从MCP获取测试数据
        test_data = await self.mcp_client.call_tool(
            "get_test_data",
            {"limit": 100}
        )
        
        return {
            "model": model_path,
            "test_samples": len(test_data.get("samples", [])),
            "metrics": {
                "accuracy": 0.91,
                "precision": 0.93,
                "recall": 0.89,
                "f1": 0.91
            }
        }

26.4 MCP + 工作流:流程自动化

26.4.1 工作流编排

class WorkflowOrchestrator:
    """工作流编排器"""
    
    def __init__(self, mcp_client):
        """初始化"""
        self.mcp_client = mcp_client
        self.workflows: Dict[str, Dict] = {}
        self.executions: List[Dict] = []
    
    def define_workflow(self, name: str, steps: List[Dict]) -> bool:
        """
        定义工作流
        
        Args:
            name: 工作流名称
            steps: 步骤列表
            
        Returns:
            是否成功
        """
        self.workflows[name] = {
            "name": name,
            "steps": steps,
            "created_at": datetime.now().isoformat()
        }
        
        return True
    
    async def execute_workflow(self, workflow_name: str,
                              inputs: Dict) -> Dict:
        """
        执行工作流
        
        Args:
            workflow_name: 工作流名称
            inputs: 输入参数
            
        Returns:
            执行结果
        """
        if workflow_name not in self.workflows:
            return {"error": "Workflow not found"}
        
        workflow = self.workflows[workflow_name]
        steps = workflow["steps"]
        current_output = inputs
        execution_log = []
        
        for step in steps:
            step_name = step.get("name")
            tool = step.get("tool")
            params_template = step.get("params", {})
            
            # 替换参数中的占位符
            params = self._resolve_params(params_template, current_output)
            
            # 执行MCP工具
            try:
                result = await self.mcp_client.call_tool(tool, params)
                
                execution_log.append({
                    "step": step_name,
                    "status": "success",
                    "result": result
                })
                
                current_output = result
            
            except Exception as e:
                execution_log.append({
                    "step": step_name,
                    "status": "error",
                    "error": str(e)
                })
                break
        
        execution = {
            "workflow": workflow_name,
            "status": "completed",
            "steps": len(execution_log),
            "execution_log": execution_log,
            "final_output": current_output,
            "executed_at": datetime.now().isoformat()
        }
        
        self.executions.append(execution)
        return execution
    
    def _resolve_params(self, template: Dict, context: Dict) -> Dict:
        """解析参数模板"""
        resolved = {}
        
        for key, value in template.items():
            if isinstance(value, str) and value.startswith("$."):
                # 从上下文获取
                path = value[2:]
                resolved[key] = context.get(path, value)
            else:
                resolved[key] = value
        
        return resolved

26.5 MCP + 多模态:扩展表达能力

26.5.1 多模态处理

class MultimodalProcessor:
    """多模态处理器"""
    
    def __init__(self, mcp_client, vision_model, audio_model):
        """初始化"""
        self.mcp_client = mcp_client
        self.vision_model = vision_model
        self.audio_model = audio_model
    
    async def process_image(self, image_path: str) -> Dict:
        """
        处理图像
        
        Args:
            image_path: 图像路径
            
        Returns:
            处理结果
        """
        # 通过MCP获取图像
        image_data = await self.mcp_client.call_tool(
            "get_image",
            {"path": image_path}
        )
        
        # 进行视觉分析
        analysis = await self.vision_model.analyze(image_data)
        
        return {
            "image": image_path,
            "objects_detected": analysis.get("objects", []),
            "description": analysis.get("description", ""),
            "text_extracted": analysis.get("text", "")
        }
    
    async def process_audio(self, audio_path: str) -> Dict:
        """
        处理音频
        
        Args:
            audio_path: 音频路径
            
        Returns:
            处理结果
        """
        # 通过MCP获取音频
        audio_data = await self.mcp_client.call_tool(
            "get_audio",
            {"path": audio_path}
        )
        
        # 进行音频分析
        result = await self.audio_model.transcribe(audio_data)
        
        return {
            "audio": audio_path,
            "transcription": result.get("text", ""),
            "language": result.get("language", "unknown"),
            "confidence": result.get("confidence", 0.0)
        }
    
    async def generate_multimodal_response(self,
                                         text: str,
                                         images: List[str] = None,
                                         audio: str = None) -> Dict:
        """
        生成多模态响应
        
        Args:
            text: 文本
            images: 图像列表
            audio: 音频路径
            
        Returns:
            多模态响应
        """
        context_parts = []
        
        # 处理文本
        context_parts.append(f"文本:{text}")
        
        # 处理图像
        if images:
            for image_path in images:
                image_analysis = await self.process_image(image_path)
                context_parts.append(
                    f"图像分析:{image_analysis['description']}"
                )
        
        # 处理音频
        if audio:
            audio_analysis = await self.process_audio(audio)
            context_parts.append(
                f"音频转录:{audio_analysis['transcription']}"
            )
        
        # 生成综合响应
        combined_context = "\n".join(context_parts)
        
        return {
            "modalities": {
                "text": bool(text),
                "images": bool(images),
                "audio": bool(audio)
            },
            "combined_context": combined_context,
            "processed_at": datetime.now().isoformat()
        }

本章总结

关键点说明
Agent系统ReAct框架、感知-规划-执行循环
RAG集成向量检索、文档增强、上下文注入
微调优化数据收集、模型调优、性能评估
工作流编排步骤定义、参数传递、错误处理
多模态图像、音频、文本的融合处理

常见问题

Q1: Agent如何与MCP协作? A: Agent通过思考-规划-动作循环调用MCP工具,形成自主决策系统。

Q2: RAG如何提升生成质量? A: 检索相关文档作为上下文注入,使模型基于真实知识生成。

Q3: 如何针对特定场景微调模型? A: 从MCP收集领域数据,经过数据准备后进行监督微调。

Q4: 工作流如何处理复杂业务流程? A: 定义步骤序列,通过参数传递实现步骤间协作。

Q5: 多模态处理有什么优势? A: 结合多种信息源进行综合分析,提升理解深度和准确性。


第四部分完成! 🎉 继续前往第五部分——项目实战篇!