--- title: "无状态 MCP 2.0 发布：Simon Willison 重燃兴趣并推出三款新工具" source: "Simon Willison 博客（Atom）" source_tier: "t2" url: "https://simonwillison.net/2026/Jul/31/stateless-mcp/#atom-everything" permalink: "https://feed.astralor.com/items/itm_7896b3091183ec3871d3f03a" published: "2026-07-31T23:13:22.000Z" score: 77 channel: "tech" tags: ["Anthropic","datasette-mcp","llm-mcp-client","mcp-explorer","Model Context Protocol"] --- # 无状态 MCP 2.0 发布：Simon Willison 重燃兴趣并推出三款新工具 ## AI 点评 > 作为 MCP 生态的早期布道者和 Datasette 作者，Simon Willison 的这次转向很有信号意味：无状态规范让工具接入门槛大幅降低，也让我更看好 MCP 重回主流 Agent 工具协议。对正在做 Agent 基础设施或 LLM 应用安全设计的人来说，他给出的三个工具和安全性观点都值得直接参考。 ## 速览 MCP 2.0（2026-07-28 规范）引入无状态调用，将原本需要两次 HTTP 请求、维护会话 ID 的流程简化为一次请求，显著降低客户端与服务器实现复杂度。Simon Willison 由此重燃对 MCP 的兴趣，并发布 mcp-explorer、datasette-mcp 与 llm-mcp-client 三款工具。他还认为，相比开放 shell 与 curl 的通用 Agent，MCP 工具更易审计和控制，更适合构建敏感应用。 ## 关键点 - 无状态 MCP 2.0（2026-07-28 规范）将工具调用简化为一次 HTTP 请求，不再需要会话 ID 和服务器端状态。 - Simon Willison 用 mcp-explorer、datasette-mcp 和 llm-mcp-client 三个项目验证新规范。 - datasette-mcp 可让 ChatGPT/Claude 对 Datasette 实例执行只读 SQL 查询。 - 他认为相比开放 shell/curl 的 Agent，MCP 工具更容易审计，更安全可靠。 ## 全文 Tuesday was Stateless MCP day - the rollout of MCP 2.0, or the 2026-07-28 Model Context Protocol specification to use the more formal but less memorable name. This is the most significant change to the MCP spec since it first launched, and has also served to reignite my personal interest in the protocol. For background: MCP is the Model Context Protocol, which describes a standard way to expose new tools to LLM-powered agent frameworks. It was introduced by Anthropic back in November 2024, had a huge spike of interest through much of 2025, and then became somewhat eclipsed by Skills (another Anthropic invention) when it became apparent that an agent harness with access to a terminal and curl could do most of what MCP did in a more flexible way. I wrote about that in my review of 2025. I'm coming back around to MCP now. Giving an agent a shell environment with the ability to access the internet is fraught with risk, and requires a strong model that is capable of effectively driving such an environment. MCP tools are easier to audit and control, and simple enough that smaller models that run on a laptop can still drive them reasonably well. The new stateless MCP specification also greatly decreases the complexity of implementing both clients and servers for the protocol. I built three of those this week! What's easier with stateless MCP The best demonstration of the difference between stateful and stateless MCP is in this May 21st blog post that introduced the RC for the new specification. It included a clear before-and-after example. The older stateful MCP (I'm going to call it "legacy MCP") required two HTTP requests - the first to initialize a session and obtain a Mcp-Session-Id, and the second to actually call the tool: POST /mcp HTTP/1.1 Content-Type: application/json { "jsonrpc": "2.0", "id": 1, "method": "initialize", "params": { "protocolVersion": "2025-11-25", "capabilities": { }, "clientInfo": { "name": "my-app", "version": "1.0" } } } POST /mcp HTTP/1.1 Mcp-Session-Id: 1868a90c-3a3f-4f5b Content-Type: application/json { "jsonrpc": "2.0", "id": 2, "method": "tools/call", "params": { "name": "search", "arguments": { "q": "otters" } } } The new stateless way uses a single HTTP request which looks like this: POST /mcp HTTP/1.1 MCP-Protocol-Version: 2026-07-28 Mcp-Method: tools/call Mcp-Name: search Content-Type: application/json { "jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": { "name": "search", "arguments": { "q": "otters" }, "_meta": { "io.modelcontextprotocol/clientInfo": { "name": "my-app", "version": "1.0" } } } } This is so much cleaner from both a client- and server-side implementation perspective. It's also a better fit for building scalable web applications, since now you don't need to maintain server-side state to keep track of those session IDs, or worry about routing the same session to the same backend machine. mcp-explorer I couldn't find a great CLI tool for interactively probing an MCP server, so I had Codex help build my own. mcp-explorer is the result. It's a stateless Python CLI tool, so you don't even need to install it to try it out - it works with uvx like this: uvx mcp-explorer list https://agentic-mermaid.dev/mcp This queries Ade Oshineye's agentic-mermaid.dev demo MCP. The above command returns the following list of tools: execute(code: string, timeoutMs?: integer) - Execute Mermaid SDK code Run JavaScript in an isolated sandbox; return a value. describe_sdk(family: string, detail?: string) - Describe Mermaid SDK operations Return version-matched mutation operations for one diagram family. render_svg(source: string, options?: object) - Render Mermaid as SVG Render a Mermaid source string to themeable SVG. Returns { ok, svg }. render_ascii(source: string, useAscii?: boolean, targetWidth?: integer, options?: object) - Render Mermaid as text Render a Mermaid source string to text. Returns { ok, text }. render_png(source: string, scale?: number, background?: string, fitTo?: object, options?: object) - Render Mermaid as PNG Rasterize a Mermaid source string to PNG. Returns { ok, png_base64 }. ... Then to inspect a tool: uvx mcp-explorer inspect render_svg This outputs a whole bunch of information, including the JSON schema of the inputs and outputs. To call that tool and pass arguments to it: uvx mcp-explorer call \ https://agentic-mermaid.dev/mcp \ render_svg \ -a source 'graph TD; A-->B' \ -a options '{"padding":24}' Which returns: {"ok":true,"svg":"