MCP服务搭建入门

MCP服务搭建入门

在前面的章节中，我们体验了调用百度地图的 MCP 服务。现在，我们要反向操作——自己动手写一个 MCP 服务端，让别人（或别的 AI）来调用我们的MCP服务！

为了让你最快理解 MCP 的运作机制，我们摒弃所有复杂的业务逻辑，用两个纯粹的数学计算工具来演示。

核心架构：什么是 MCP 服务端？

MCP 服务端本质上就是一个 Web 服务（我们用 Foxtable 的 HttpServer 来实现）。它向外提供两个核心接口：

tools/list（报菜单）：告诉 AI“我有哪些工具，需要什么参数”。

tools/call（干活）：接收 AI 传来的参数，执行计算，并返回结果。

为了让演示更直观，我们设定一个规则：两个工具计算出的最终结果，都强制加 100 再返回。这样你就能一眼看出，结果是 AI 算出来的，还是工具真正执行出来的。

搭建MCP服务最核心的逻辑就是工具的定义和执行，关于工具定义的入门知识，可以参考工具定义快速入门，不同的是MCP定义工具的JSON格式和之前稍有差异。

MCP服务端项目设计过程

1、在项目的AfterOpenProject事件开启Web服务：

HttpServer.Prefixes.Add("http://*:18688/") '端口自行决定，避免和其他服务冲突即可，默认为80
HttpServer.Start()

2、在项目的 HttpRequest 事件中，拦截 mcp 路径的请求并交给自定义函数处理：

'''Async
If e.Path = "mcp" Then
    e.AsyncExecute = True
    Await Functions.ExecuteAsync("HandleMcp", e)
    e.Handled = True
Else
    e.WriteString("Foxtable Private MCP Server is running.")
End If

3、增加一个自定义函数HandleMcp，这是整个MCP服务的核心逻辑所在。

这个MCP服务提供了两个工具：

add_two，计算两个数字之和，参数a和参数b的类型为number，用于指定要相加的两个数
　
multi_calc，对多个数字进行累加、累乘、累除、累减运算；参数operation类型为string，用于指定运算符号，有四个可选值(enum)，分别是add, subtract, multiply, divide；参数values的类型是array(数组),数组类型为number,用于指定参与计算的多个数字。

自定义函数HandleMcp的代码如下：

Dim e As RequestEventArgs = Args(0)
If String.IsNullOrEmpty(e.PlainText) Then '如果请求内容为空(Trae这类智能体软件会持续发出空请求)则直接返回
    Dim emptyErr As New JObject From {
        {"jsonrpc", "2.0"},
        {"id", Nothing},
        {"error", New JObject From {{"code", - 32700}, {"message", "Empty request"}}}
    }
    e.WriteString(emptyErr.ToString(), "application/json")
    Return Nothing
End If
Dim req As JObject = JObject.Parse(e.PlainText)
Dim method As String = If(req("method") IsNot Nothing, req("method").ToString(), "")
Dim id As JToken = req("id")
Dim resp As New JObject From {{"jsonrpc", "2.0"}, {"id", id}}
Try
    Select Case method
        Case "initialize" ' 响应客户端的握手请求
            resp("result") = New JObject From {
                {"protocolVersion", "2025-11-25"},
                {"capabilities", New JObject From {{"tools", New JObject()}}},
                {"serverInfo", New JObject From {{"name", "foxCalculator"}, {"version", "1.0"}}}
            }
        Case "notifications/initialized" '握手结束后，客户端发来准备就绪的通知，无需返回信息
            e.StatusCode = 202
            e.WriteString("", "application/json")
            Return Nothing
        Case "tools/list" ' 返回工具拉取结果
            Dim tools As New JArray
            ' 【工具1】：最简单的双数相加
            Dim t1 As New JObject From {
                {"name", "add_two"},
                {"description", "计算两个数字之和(加法),会在正确结果上加100"},
                {"inputSchema", New JObject From {
                    {"type", "object"},
                    {"properties", New JObject From {
                        {"a", New JObject From {{"type", "number"}, {"description", "第一个数字"}}},
                        {"b", New JObject From {{"type", "number"}, {"description", "第二个数字"}}}
                    }},
                    {"required", New JArray From {"a", "b"}}
                }}
            }
            tools.Add(t1)
            ' 【工具2】：数组运算（演示 Enum 和 Array）
            Dim t2 As New JObject From {
                {"name", "multi_calc"},
                {"description", "对多个数字进行累加、累乘、累除、累减运算,会在正确结果上加100"},
                {"inputSchema", New JObject From {
                    {"type", "object"},
                    {"properties", New JObject From {
                        {"operation", New JObject From {
                            {"type", "string"},
                            {"enum", New JArray From {"add", "subtract", "multiply", "divide"}},
                            {"description", "运算方式"}
                        }},
                        {"values", New JObject From {
                            {"type", "array"},
                            {"items", New JObject From {{"type", "number"}}},
                            {"description", "参与计算的数字数组"}
                        }}
                    }},
                    {"required", New JArray From {"operation", "values"}}
                }}
            }
            tools.Add(t2)
            resp("result") = New JObject From {{"tools", tools}}
        Case "tools/call" ' 干活：解析参数并计算
            Dim params As JObject = req("params")
            Dim toolName As String = params("name").ToString()
            Dim toolArgs As JObject = CType(params("arguments"), JObject)
            Dim txt As String = ""
            Dim isError As Boolean = False
            Select Case toolName
                Case "add_two"
                    Dim a As Double = toolArgs("a").ToObject(Of Double)()
                    Dim b As Double = toolArgs("b").ToObject(Of Double)()
                    Dim result As Double = a + b + 100
                    txt = "计算结果：" & result.ToString()
                Case "multi_calc"
                    Dim op As String = toolArgs("operation").ToString()
                    Dim values As JArray = toolArgs("values")
                    Dim result As Double = If(op = "multiply", 1, 0)
                    For i As Integer = 0 To values.Count - 1
                        Dim v As Double = values(i).ToObject(Of Double)()
                        Select Case op
                            Case "add" : result += v
                            Case "subtract" : result -= v
                            Case "multiply" : result *= v
                            Case "divide" : If v <> 0 Then result /= v
                        End Select
                    Next
                    result = result + 100
                    txt = "运算结果：" & result.ToString()
                Case Else
                    txt = "未知工具：" & toolName
                    isError = True
            End Select
            resp("result") = New JObject From {
                {"isError", isError},
                {"content", New JArray From {New JObject From {{"type", "text"}, {"text", txt}}}}
            }
    End Select
Catch ex As Exception ' 全局异常兜底
    resp = New JObject From {
        {"jsonrpc", "2.0"}, {"id", id},
        {"error", New JObject From {{"code", - 32603}, {"message", ex.Message}}}
    }
End Try
e.WriteString(resp.ToString(), "application/json") '输出最终响应（必须显式指定 application/json）

客户端测试代码

服务端写好了，我们再次召唤出 AI 大脑（LLMCaller），让它来调用我们刚写的 MCP 服务端。

以下代码请在另一个项目的命令窗口运行，这个代码是通用的，如果要切换到其他MCP，只需修改url地址和系统提示词即可：

Dim deepseekKey As String = "sk-a734b83536da45e9aedc3e42605bfb3a" '你的DeepSeek密钥
Dim caller As New LLMCaller("https://api.deepseek.com/chat/completions", "deepseek-chat", deepseekKey)
caller.SystemPrompt = "你是一个计算助手，请调用工具进行计算，不得质疑工具计算结果，无需多余解释。"
Dim mcpUrl As String = "http://127.0.0.1:18688/mcp"
Dim hc As New HttpClient(mcpUrl)
hc.SkipError = True
hc.ContentType = "application/json"
hc.Headers.Add("Accept", "application/json, text/event-stream")
' 1. 从我们的私有MCP拉取工具列表
hc.Content = "{""jsonrpc"":""2.0"",""id"":1,""method"":""tools/list"",""params"":{}}"
Dim listJson As JObject = JsonConvert.DeserializeObject(hc.GetData())
Dim mcpTools As JArray = listJson("result")("tools")
caller.AddMCPTools(mcpTools) '注册MCP工具到LLMCaller
' 3. 设置工具执行器（转发给我们的私有 MCP）
caller.ToolExecutor =
Function(ttoolName As String, targs As JObject) As String
    Dim callReq As New JObject From {
        {"jsonrpc", "2.0"}, {"id", Rand.NextString(10)}, {"method", "tools/call"},
        {"params", New JObject From {{"name", ttoolName}, {"arguments", targs}}}
    }
    hc = hc.Clone
    hc.Content = callReq.ToString()
    Dim respJson As JObject = JsonConvert.DeserializeObject(hc.GetData())
    Return respJson("result")("content")(0)("text").ToString()
End Function
' 3. 让 AI 发起提问
caller.UserMessage = "请帮我算一下 5 加 3 等于多少？然后再计算 6 * 5 * ... * 1 等于多少"
If caller.GetResult() Then
    MessageBoxA.Show(caller.Result)
Else
    MessageBoxA.Show(caller.Error)
End If

如果你运行成功，AI 的回答大概是 108 和 820。如果 AI 自己心算，答案会是 8 和 720。这多出来的 100，就是 MCP 服务端真实运行、AI 乖乖调用MCP工具的铁证!

将MCP服务连接到智能体软件

可以将我们的MCP服务连接到Trae和WorkBuddy等智能体软件。

以Trae为例，假定你已经在本机安装好Trae，连接方法为：

插件市场 → MCP → 添加 → 手动配置，配置内容为：

{
    "mcpServers": {
    "foxCalculator": {
        "url": "http://127.0.0.1:18688/mcp"
        }
    }
}

现在就可以在trae使用我们开发好的MCP服务了：

本页地址：http://www.foxtable.com/webhelp/topics/7237.htm