- 1Anthropic releases MCP as open specification (November 2024)
- 2Google donates A2A to the Linux Foundation; MCP remains under Anthropic's open spec working group (2025-2026)
- 3HTTP+SSE transport deprecated in favor of Streamable HTTP (spec revision 2025-03-26)
- 4Cursor, Continue, and Zed adopt MCP as their tool connectivity standard (early 2025)
- 5OWASP branded community MCP risk taxonomy emerges, cataloging tool poisoning, rug pulls, and confused deputy threats (2025)
MCP: November 2024 release, early-2025 IDE adoption, March-2025 SSE-to-Streamable-HTTP transport, 2025 community security taxonomy, then a 2025-2026 split (A2A → Linux Foundation, MCP stays under Anthropic).
Picture how a new electrical plug shape catches on. First one company designs the plug and publishes the blueprint so anyone can build to it. Then a few gadget makers adopt it because it is convenient. As more devices use it, the original designers notice the early wiring was clunky, so they swap it for a cleaner version. Safety inspectors then write a checklist of ways the plug can be misused. Finally, once half the industry depends on it, no single company should own the standard, so it moves to a neutral committee. MCP followed that exact arc: release, early adoption, a transport upgrade, a security checklist, and shared governance.
Concept explanation~2 min read
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Concept explanation~2 min read
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Timeline-ordering questions look like trivia, but the good ones are really testing whether you understand cause and effect. The MCP origin timeline is a clean example. If you grasp why each milestone enables the next, you can reconstruct the whole order even when the exact months slip your memory. Interviewers love this format because it separates candidates who memorized a press release from candidates who actually understand how a protocol matures.
The core question is, 'what had to be true before each event could happen?' A protocol must exist before anyone adopts it. Adoption must happen before usage exposes design flaws. Real deployment must exist before security researchers can catalog concrete attacks. And broad multi-vendor dependence must build up before neutral governance becomes worthwhile. Each link in that chain is a hard prerequisite, not a soft preference, which is what makes the ordering robust.
Notice that two of the five events share the same calendar year, 2025. The transport revision and the security taxonomy both land then. That is the one place where dates alone leave the order ambiguous, so you fall back on the finer-grained causal argument to separate them. This deep dive walks the five milestones in order, explains the dependency that pins each one in place, and gives you the language to defend the ordering under follow-up pressure.
Milestone 1: the open-spec release (November 2024)
Everything starts with Anthropic publishing MCP as an open specification in November 2024. This is the root of the dependency graph, and nothing in the timeline can precede it. You cannot adopt, refine, secure, or govern a protocol that does not yet exist. In an ordering question this is the easiest anchor to plant first, because the other four events all reference it implicitly.
The word open is doing real work here. MCP shipped not as an Anthropic-internal feature but as a public spec any vendor could implement. Anthropic paired the launch with reference servers for filesystem, Git, and Postgres access, plus Claude Desktop as the first host that spoke the protocol. Shipping reference servers alongside the spec mattered, because it gave implementers a concrete target rather than a document to interpret.
That openness is precisely what unlocked the next step. A closed, single-vendor API would never have triggered an industry-wide adoption wave. Because the spec and SDKs were public, third-party editors could build compliant clients without permission or partnership. The protocol was deliberately framed around JSON-RPC and a small set of primitives, tools, resources, and prompts, so the implementation cost for a new client stayed low. That low cost is what made the early-2025 adoption wave plausible in the first place.
Situations where this technique stops working.
2–4 min · Everything important, quickly.
| Step | Event | Why it sits here |
|---|---|---|
| 1 | Anthropic releases MCP open spec (Nov 2024) | Root event; nothing can precede the spec existing |
| 2 | Cursor, Continue, Zed adopt MCP (early 2025) | Adoption requires an existing open standard |
| 3 | HTTP+SSE deprecated for Streamable HTTP (mid-2025) | Transport pain surfaces only after real remote use |
| 4 | OWASP MCP Top 10 published (2025) | Security taxonomy follows a deployed attack surface |
| 5 | Governance maturation: A2A donated to Linux Foundation (2025); MCP stays under Anthropic's open spec (2025-2026) | Neutral foundation stewardship is the canonical move once a protocol matters to many vendors; A2A has made it, MCP has not yet |
Real products, models, and research that use this idea.
- Anthropic shipped MCP in November 2024 with reference servers for filesystem, Git, and Postgres, plus Claude Desktop as the first host.
- Cursor, Continue, and Zed adopted MCP in early 2025, so a server written once ran across all three editors without rewrites.
What an interviewer would ask next. Try answering before peeking at the approach.
QWhy did the original HTTP+SSE transport get deprecated, and what does Streamable HTTP do better?
HTTP+SSE needed two endpoints and a long-lived connection, awkward for serverless. Streamable HTTP uses one endpoint with optional streaming, fitting stateless remote hosting.
Red flags & common mistakes
The phrases that signal junior thinking. Click to expand.
Red flags & common mistakes
The phrases that signal junior thinking. Click to expand.
Putting adoption before the release, or assuming the security taxonomy came first. Tools could not adopt a spec that did not exist yet, and security work follows usage.
60 second bullets to scan on the way to the call.
Why the open-spec release must be the first event
Why adoption cannot precede the specification
Primary sources. Browse if you want the original framing.
Same topic, related formats. Practice these next.