MCP
Model Context Protocol · JSON-RPC-based protocol for connecting LLM clients to data sources and tools.
Status
ActiveVersion
Updated
Steward
Specification: https://modelcontextprotocol.io
Editorial note
MCP is the closest thing the category has to a winning interop standard for the tool-and-data layer. Adoption has crossed the threshold where new clients are expected to support it.
Our analysis
MCP's design choice — a JSON-RPC layer over the host transport, with a small core of resource, prompt, and tool primitives — is conservative on purpose, and the conservatism is what has let it spread. The protocol does not try to specify identity, billing, or rate limiting; it stays in the lane of "how does a client ask a server for context." That restraint is the reason a long tail of community servers exists. Where the spec gets contested is at the seams: streaming behavior across long-running tool calls, the semantics of resource subscriptions, and the interaction between MCP and host-side audit. We expect the next year's working-group time to land mostly on those seams rather than on new primitives. Skeptics of MCP point out that the spec is governed informally and that a sponsor-led standard is structurally different from a vendor-neutral one; the more pragmatic answer is that there is no IETF process happening for this layer and there isn't going to be one. MCP is what we have. The serious vendors are shipping against it.
What we are watching
- Resource subscription semantics for long-running tool calls
- How MCP interacts with the per-agent identity story (see /standards/agent-id/)
- Whether OpenAgents and MCP converge or diverge in 2027
How to cite this entry
Citation format: The Agentic Review. "MCP — Model Context Protocol." Standards Tracker, last
updated 2026-04-12. https://agentic.review/standards/mcp/.
See our citation style for additional guidance.