MCP Server Cards (ext-server-card, SEP-2127)

Linux Foundationspecificationcore entry

Verified 2026-10-13. Status as of 2026-10-13. All entries.

Seams: S1

Status

Experimental extension of MCP: the README of the extension repository still reads "not an accepted or official MCP extension" (2026-10-13). SEP-2127 (PR #2127, "MCP Server Cards - HTTP Server Discovery", Extensions Track) was merged on 2026-10-06 (14:43 UTC, merge commit 0a11bf6) by a maintainer of the MCP repository; the Specification Enhancement Proposal (SEP) file, read 2026-10-13, carries "Status: Final" and says the full extension specification stays in the extension repository, graduating to a repository named ext-server-card on acceptance. The last commit of the extension repository on main is of 2026-08-12 (PR #47); latest activity read: issue #30 (2026-10-10, 9 comments).

Relevance

A Server Card is "a static metadata document that describes a remote MCP server enough for clients to discover and connect to it"; cards "intentionally omit primitive listings (tools, resources, prompts)". docs/discovery.md says clients performing domain-level discovery SHOULD attempt to retrieve /.well-known/ai-catalog.json, whose entries of type application/mcp-server-card+json point to the cards.

Commerce metadata was kept out of the card: in issue #27 (closed 2026-06-13) a member of the modelcontextprotocol organisation (GitHub author association MEMBER, read 2026-10-13) answered "we do not intend to introduce MCP-specific patterns (like _meta) into the MCP Catalog"; SEP-2007 (payment support) was closed 2026-06-24 as "dormant".

Committed next

• Roadmap (PR #47, merged 2026-08-12): graduate the Server Card as an official MCP extension, then static primitives (#30) and authentication (#13). (undated) [maintainer or chair statement] https://github.com/modelcontextprotocol/ext-server-card/pull/47
• Notes of 2026-07-20: "Nested catalog and Link header features deferred to after release." (undated) [maintainer or chair statement] https://github.com/modelcontextprotocol/modelcontextprotocol/discussions/3115

Boundary

The README says a Server Card "describes remote connectivity only"; local installation metadata stays in the MCP Registry server.json.

Sources

• https://github.com/modelcontextprotocol/ext-server-card normative text, read 2026-10-13 · archived
• https://github.com/modelcontextprotocol/ext-server-card/blob/main/docs/discovery.md normative text, read 2026-10-02 · archived
• https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2127 maintainer or chair statement, read 2026-10-13 · archived
• https://github.com/modelcontextprotocol/ext-server-card/pull/47 maintainer or chair statement, read 2026-10-13 · archived
• https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/seps/2127-mcp-server-cards.md official decision or commitment, read 2026-10-13 · archived
• https://github.com/modelcontextprotocol/modelcontextprotocol/discussions/3115 participant or third party, read 2026-10-03 · archived
• https://github.com/modelcontextprotocol/ext-server-card/issues/27 participant or third party, read 2026-10-03 · archived

Overlaps

AI Catalog (Agent Card Working Group), A2A protocol, agent discovery, Agentic Resource Discovery (ARD), Model Context Protocol (MCP), core specification

Neighbours in the map

Solid lines: overlaps declared by one of the two entries. Dashed lines, coloured by seam: entries named by the same seam (S1 to S4) in the seams note. Every node is a link.

Evidence and coverage

Read

On 2026-10-13: PR #2127 with its labels and files, the SEP file seps/2127-mcp-server-cards.md, the README of the extension repository and the state of PR #47 and issues #13, #30, #43, #44, #48 and #50. ext-server-card: README, discovery.md, all issues and PRs in full; core repository since 2026-01-01: PR #2127, notes, Discussions #2831, #2896.

Not read

Issue #1649 comments, Core Maintainer meetings, external links.

Not found

Not found there (2026-10-03): GTIN, GS1.

Open proposals