MCP Tool 实现进度通知

本文档使用C#语言，引用类库ModelContextProtocol 1.1.0。

首先了解一下怎么通知。mcp可使用Json-RPC协议进行通信，在通信时，需要带上唯一的Id。在ModelContextProtocol类库中提供SendNotificationAsync进行实现。

ModelContextProtocol官方实例：

using ModelContextProtocol; using ModelContextProtocol.Protocol; using ModelContextProtocol.Server; using System.ComponentModel; namespace EverythingServer.Tools; [McpServerToolType] public class LongRunningTool { [McpServerTool(Name = "longRunningOperation"), Description("Demonstrates a long running operation with progress updates")] public static async Task<string> LongRunningOperation( McpServer server, RequestContext<CallToolRequestParams> context, int duration = 10, int steps = 5) { var progressToken = context.Params?.ProgressToken; var stepDuration = duration / steps; for (int i = 1; i <= steps + 1; i++) { await Task.Delay(stepDuration * 1000); if (progressToken is not null) { //参数1：可以自定义，根据业务进行调整； //参数2：通知的主要内容。 await server.SendNotificationAsync("notifications/progress", new { DataTime=DateTime.Now, Progress = i, Total = steps, progressToken }); } } return $"Long running operation completed. Duration: {duration} seconds. Steps: {steps}."; } }

测试结果

首先初始化获取SessionId参数

//请求内容 { "id": 1, "jsonrpc": "2.0", "method": "initialize" } //注：返回的SessionId在结果的Header中。

请求方式：Post，Header中添加Mcp-Session-Id

{ "id": 5, "jsonrpc": "2.0", "method": "tools/call", "params": { "arguments": { "duration": 10, "steps": 5 }, "name": "longRunningOperation", "_meta": { "progressToken": "5", } } }

返回结果

event: message data: {"method":"notifications/progress","params":{"dataTime":"2026-03-12T11:24:02.0650511\u002B08:00","progress":1,"total":5,"progressToken":"5","_meta":{"traceparent":"00-42c8e08ad79e37e2994a3281d4dd4f40-12481cb00442bda3-01"}},"jsonrpc":"2.0"} event: message data: {"method":"notifications/progress","params":{"dataTime":"2026-03-12T11:24:04.1063487\u002B08:00","progress":2,"total":5,"progressToken":"5","_meta":{"traceparent":"00-42c8e08ad79e37e2994a3281d4dd4f40-8fb8fe66e322a794-01"}},"jsonrpc":"2.0"} event: message data: {"method":"notifications/progress","params":{"dataTime":"2026-03-12T11:24:06.1136731\u002B08:00","progress":3,"total":5,"progressToken":"5","_meta":{"traceparent":"00-42c8e08ad79e37e2994a3281d4dd4f40-c8d9c44f655556b5-01"}},"jsonrpc":"2.0"} event: message data: {"method":"notifications/progress","params":{"dataTime":"2026-03-12T11:24:08.117121\u002B08:00","progress":4,"total":5,"progressToken":"5","_meta":{"traceparent":"00-42c8e08ad79e37e2994a3281d4dd4f40-d13d9d41491839e7-01"}},"jsonrpc":"2.0"} event: message data: {"method":"notifications/progress","params":{"dataTime":"2026-03-12T11:24:10.129892\u002B08:00","progress":5,"total":5,"progressToken":"5","_meta":{"traceparent":"00-42c8e08ad79e37e2994a3281d4dd4f40-5ae4e347dddb7722-01"}},"jsonrpc":"2.0"} event: message data: {"method":"notifications/progress","params":{"dataTime":"2026-03-12T11:24:12.1450282\u002B08:00","progress":6,"total":5,"progressToken":"5","_meta":{"traceparent":"00-42c8e08ad79e37e2994a3281d4dd4f40-c43f7141197de3cd-01"}},"jsonrpc":"2.0"} event: message data: {"result":{"content":[{"type":"text","text":"Long running operation completed. Duration: 10 seconds. Steps: 5."}]},"id":5,"jsonrpc":"2.0"}