--- title: Did Anthropic finally fix MCP? | daily.dev description: Anthropic released MCP 2026-07-28, a major revision to the Model Context Protocol that moves from a stateful, bidirectional connection model to a stateless... canonical: https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Did Anthropic finally fix MCP? | daily.dev og:description: Anthropic released MCP 2026-07-28, a major revision to the Model Context Protocol that moves from a stateful, bidirectional connection model to a stateless... og:url: https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf og:image: https://api.daily.dev/og/posts/IEg7bzOKf.png og:image:alt: Did Anthropic finally fix MCP? og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Did Anthropic finally fix MCP? **[Theo - t3․gg](https://daily.dev/sources/t3dotgg)** · 18 min read · 0 upvotes · 0 comments ## Summary Anthropic released MCP 2026-07-28, a major revision to the Model Context Protocol that moves from a stateful, bidirectional connection model to a stateless request-response architecture. Previously, every MCP server required a persistent dedicated connection to the client — even when unused — causing significant resource overhead, especially with sub-agents spawning dozens of simultaneous connections. The new stateless design lets MCP servers run on serverless infrastructure like Lambda or Cloudflare Workers, eliminates the need for sticky routing and session management, and reduces client-server interaction from two HTTP requests to one. Simon Willison built three MCP servers in a week using the new spec and found it dramatically simpler. The main concern raised is backwards incompatibility: old clients expect stateful connections and cannot work with new stateless servers, creating fragmentation risk. However, the argument is that LLMs make updating client implementations fast enough that any tool not upgrading quickly is signaling poor development velocity. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What changed in the MCP 2026-07-28 spec compared to the old Model Context Protocol? MCP 2026-07-28 moves from a bidirectional stateful protocol to a stateless request-response model. The old spec required two HTTP requests — one to initialize a session and obtain an ID, and a second to call tools — with sticky routing to keep sessions bound to the same server. The new spec uses a single HTTP request per tool call, requires no session state, and allows MCP servers to run on serverless or edge infrastructure like Lambda or Cloudflare Workers. _Teams shipping MCP integrations track spec changes like this on daily.dev before they get caught with incompatible client implementations._ ### Why did stateful MCP cause so much resource overhead with sub-agents in tools like Codex? Each MCP server required a persistent dedicated connection to the client for the entire duration of a session, even if never called. With sub-agents, one Codex run spawning five sub-agents with six MCP servers each created 30 stateful server processes and 30 client-side bound connections simultaneously — all for a single prompt. On macOS, this caused sisypolicyd to spike CPU usage because the OS flagged the mass of spawned server processes as suspicious. _Developers building multi-agent pipelines stay ahead of infrastructure gotchas like these on daily.dev._ ### Is the new stateless MCP spec backwards compatible with old MCP clients? No, the new stateless MCP spec is not backwards compatible with old clients. Old client implementations expect a persistent stateful connection to be established and maintained. The new spec is the opposite — a simple HTTP request-response with no session binding. A new stateless MCP server cannot be used by a client that only supports the legacy stateful protocol, creating fragmentation between tools that have and haven't updated their MCP bindings. _Choosing which agentic tools to build on gets easier when you follow MCP ecosystem updates on daily.dev._ ## Similar posts on daily.dev - [Stateless MCP Removes Session Affinity Requirements for AWS Server Deployments](https://daily.dev/posts/stateless-mcp-removes-session-affinity-requirements-for-aws-server-deployments-iygc8pbe0) · InfoQ · 1 upvotes · 0 comments - [One Year of MCP: Looking Back, and Forward](https://daily.dev/posts/one-year-of-mcp-looking-back-and-forward-ymkm9aqzq) · The New Stack · 1 upvotes · 0 comments - [MCP is now stateless: what the 2026-07-28 update changes](https://daily.dev/posts/mcp-is-now-stateless-what-the-2026-07-28-update-changes-hc2vhg5ll) · Flavio Copes · 9 upvotes · 0 comments --- Tags: [#ai-agents](https://daily.dev/tags/ai-agents), [#serverless](https://daily.dev/tags/serverless), [#mcp](https://daily.dev/tags/mcp), [#anthropic](https://daily.dev/tags/anthropic) [View this post on daily.dev](https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Did Anthropic finally fix MCP?","url":"https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf"},"datePublished":"2026-08-08T23:22:55.282Z","dateModified":"2026-08-12T10:03:47.543Z","description":"Anthropic released MCP 2026-07-28, a major revision to the Model Context Protocol that moves from a stateful, bidirectional connection model to a stateless...","image":"https://i.ytimg.com/vi/gVfEtktkvnE/sddefault.jpg","thumbnailUrl":"https://i.ytimg.com/vi/gVfEtktkvnE/sddefault.jpg","isAccessibleForFree":true,"articleSection":"Theo - t3․gg","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Theo - t3․gg","logo":"https://media.daily.dev/image/upload/s--UmX7IyU3--/f_auto/v1704628081/logos/t3dotgg.jpg","url":"https://daily.dev/sources/t3dotgg"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"ai-agents,serverless,mcp,anthropic","timeRequired":"PT18M","video":{"@type":"VideoObject","name":"Did Anthropic finally fix MCP?","description":"Anthropic released MCP 2026-07-28, a major revision to the Model Context Protocol that moves from a stateful, bidirectional connection model to a stateless...","thumbnailUrl":"https://i.ytimg.com/vi/gVfEtktkvnE/sddefault.jpg","uploadDate":"2026-08-08T23:22:55.282Z","duration":"PT18M","url":"https://api.daily.dev/r/IEg7bzOKf","embedUrl":"https://www.youtube.com/embed/gVfEtktkvnE"}} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Theo - t3․gg","item":"https://daily.dev/sources/t3dotgg"},{"@type":"ListItem","position":3,"name":"Did Anthropic finally fix MCP?"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/did-anthropic-finally-fix-mcp--ieg7bzokf#faq","mainEntity":[{"@type":"Question","name":"What changed in the MCP 2026-07-28 spec compared to the old Model Context Protocol?","acceptedAnswer":{"@type":"Answer","text":"MCP 2026-07-28 moves from a bidirectional stateful protocol to a stateless request-response model. The old spec required two HTTP requests — one to initialize a session and obtain an ID, and a second to call tools — with sticky routing to keep sessions bound to the same server. The new spec uses a single HTTP request per tool call, requires no session state, and allows MCP servers to run on serverless or edge infrastructure like Lambda or Cloudflare Workers. Teams shipping MCP integrations track spec changes like this on daily.dev before they get caught with incompatible client implementations."}},{"@type":"Question","name":"Why did stateful MCP cause so much resource overhead with sub-agents in tools like Codex?","acceptedAnswer":{"@type":"Answer","text":"Each MCP server required a persistent dedicated connection to the client for the entire duration of a session, even if never called. With sub-agents, one Codex run spawning five sub-agents with six MCP servers each created 30 stateful server processes and 30 client-side bound connections simultaneously — all for a single prompt. On macOS, this caused sisypolicyd to spike CPU usage because the OS flagged the mass of spawned server processes as suspicious. Developers building multi-agent pipelines stay ahead of infrastructure gotchas like these on daily.dev."}},{"@type":"Question","name":"Is the new stateless MCP spec backwards compatible with old MCP clients?","acceptedAnswer":{"@type":"Answer","text":"No, the new stateless MCP spec is not backwards compatible with old clients. Old client implementations expect a persistent stateful connection to be established and maintained. The new spec is the opposite — a simple HTTP request-response with no session binding. A new stateless MCP server cannot be used by a client that only supports the legacy stateful protocol, creating fragmentation between tools that have and haven't updated their MCP bindings. Choosing which agentic tools to build on gets easier when you follow MCP ecosystem updates on daily.dev."}}]} ```