Model Context Protocol — staged 2026-08-11

Provenance

File	Source URL	Fetched	Completeness
CHANGELOG-2026-07-28.md	https://modelcontextprotocol.io/specification/2026-07-28/changelog.md	2026-08-11	COMPLETE, verbatim
schema.json	https://raw.githubusercontent.com/modelcontextprotocol/modelcontextprotocol/main/schema/2026-07-28/schema.json	2026-08-11 (see caveat)	COMPLETE, but copied from the 2026-08-10 local baseline, not from today’s fetch
registry-server.schema.json	https://raw.githubusercontent.com/modelcontextprotocol/registry/main/docs/reference/server-json/draft/server.schema.json	2026-08-11	COMPLETE, verbatim

Current protocol revision

2026-07-28 — this is the latest released revision. It is what https://modelcontextprotocol.io/specification/latest resolves to and what llms.txt indexes. There is no revision string literally named “v2”; the colloquial “MCP v2” refers to this revision, which is the first genuinely breaking redesign (stateless, no initialize, no sessions, MRTR instead of server-initiated requests).

schema/draft/schema.json on main is currently byte-for-byte equivalent in size and structure to schema/2026-07-28/schema.json — i.e. no new draft revision has diverged yet as of 2026-08-11.

schema.json caveat (IMPORTANT)

web_fetch truncates at ~132 KB. The upstream schema.json is ~181 KB / 3963 lines / 155 $defs. Today’s fetch returned only the first 2893 lines (118 $defs, ending mid-object inside ResourceRequestParams). The rules for this task forbid curl/wget, so a complete verbatim re-fetch was not possible.

What was verified: the truncated portion of today’s fetch matches the 2026-08-10 baseline exactly — same 4-space formatting, same 118 $defs in the same order, same line-for-line prefix. The file here is the complete baseline copy. Treat it as revision 2026-07-28 with high but not byte-proven confidence. To get a byte-exact copy, clone the repo or use an HTTP client without a response size cap.

Registry / server manifest

registry-server.schema.json is the server.json format used by the official MCP Registry (https://registry.modelcontextprotocol.io). It is JSON Schema draft-07 (not 2020-12) and is auto-generated from docs/reference/api/openapi.yaml.

Required fields on ServerDetail: name, description, version.

• name — reverse-DNS with exactly one /, e.g. io.github.user/weather, pattern ^[a-zA-Z0-9.-]+/[a-zA-Z0-9._-]+$, 3–200 chars.
• description — 1–100 chars (note the tight 100-char cap).
• version — max 255 chars, SHOULD be semver; ranges and latest are rejected.

Registry notes (from https://modelcontextprotocol.io/registry/about.md, fetched 2026-08-11): registry is in preview; it does not accept private servers — for internal Patterson servers the guidance is to run a private registry implementing the official OpenAPI spec (docs/reference/api/openapi.yaml in modelcontextprotocol/registry). Namespace ownership is proven by DNS / GitHub / HTTP challenge.

MCP Apps / UI extensions

MCP Apps is an extension, not core spec. Current spec directory upstream is specification/2026-01-26/apps.mdx in modelcontextprotocol/ext-apps. See ../mcp-apps/. Key wire facts: tool declares _meta.ui.resourceUri pointing at a ui:// resource; host fetches the HTML resource and renders it in a sandboxed iframe; app<->host talk over postMessage JSON-RPC with ui/-prefixed methods plus shared tools/call; _meta.ui.csp and _meta.ui.permissions control external origins and capabilities.

Other official extensions as of 2026-08-11: io.modelcontextprotocol/tasks (async execution), OAuth client credentials, enterprise-managed authorization. See https://modelcontextprotocol.io/extensions/overview.md and https://modelcontextprotocol.io/extensions/client-matrix.md.