c1fa4f315e* docs: add skills-extension-candidates tracker Scaffold a candidates list for MCP servers, dev tools, SDKs, and skills repositories that could adopt SEP-2640. Initial entries: FastMCP 3.0 Skills, chrome-devtools-mcp, hf-mcp-server, Hugging Face skills library, github-mcp-server (PR #2428 demo), Azure Skills Plugin. Cross-link from related-work.md and add a row to the README docs table. * docs: add Issue/PR tracker column to candidates table * docs: add client-mcp-support survey alongside candidates tracker * docs: link Azure MCP Server source in candidates table * docs: remove gemini-cli from client MCP support survey * docs: verify hermes-agent, switch source refs to main-branch links, refresh takeaways - Promote hermes-agent from first-pass to verified; note its per-server tool pattern (`mcp_{server}_read_resource` + `mcp_{server}_list_resources`) and confirm end-user docs exist - Drop stale line numbers throughout; convert path refs to GitHub source-file links on `main` (commit-pinned URLs decayed once files moved) - Goose: PR #8989 has landed, so describe current `(extension_name, uri)` required signature and drop the now-closed issue/PR tracking - Takeaways: collapse to three implementation patterns (Goose now fits the `(server, uri)` bucket), fix open-source count to fourteen, drop the smolagents name-drop (not in survey), add strands-agents alongside mastra for the internal-SDK-only pattern, and reframe the signature recommendation around server-resolution reliability rather than URI portability * docs: verify remaining first-pass clients, flip cline/Roo-Code to Yes Verified adk-python, agent-framework, crewAI, mastra, cline, Roo-Code against local source clones. Two corrections to prior state: - cline and Roo-Code both expose access_mcp_resource(server, uri) as a model-facing tool via McpHub.readResource. Flipped from No to Yes. - adk-python's load_mcp_resource takes resource_names: array[string] in a single call (not two-shot); opt-in via use_mcp_resources flag. Headline count updated from six to eight of fourteen open-source clients satisfying #2527. Cross-cutting observations and takeaways adjusted for the new (server, uri) family members and the four-pattern signature breakdown. Trust-model list extended. * docs: add Figma and Adobe MCP as SEP-2640 testing candidates * docs: update FastMCP 3.0 Skills entry with detailed notes on SEP-2640 compliance * docs: drop unconfirmed Cursor SEP-2640 entry, track latest SEP-2640 wire-contract PRs Remove the Cursor row + deep dive (reported WIP never confirmed). Add the in-flight PRs realigning to the 2026-06-05/06-09 SEP-2640 schema (frontmatter + archives[] index, resources/directory/read): hf-mcp-server#174, fast-agent#825, huggingface/skills#172. * docs: add Slack (interested) and Bloomberg (internal use) as SEP-2640 candidates * docs: remove archived Roo-Code from client survey, update strands repo to harness-sdk * docs: re-verify SEP-2640 implementations against current upstream main Both reference implementations have migrated to the July 2026 v1 shape, verified against fresh clones rather than the prior June commit pins: - hf-mcp-server (d794b10, v0.4.6): skills/list + skills/get, per-file {uri,digest} resources manifest, directoryRead:true, no index.json or archives. Migrated in #219 (merged 2026-08-03). Also records the snapshot/TTL model and HTTP-transport-only constraint. - fast-agent (79b903c, 0.10.1): pins SEP-2640 revision d7490ec, treats legacy index.json skill-md/archive entries as unsupported. Requires --prerelease=allow (pins fastmcp-slim 4.0.0b1), per @evalstate. Corrects the earlier note claiming implementations lagged the SEP: the #174/#825/#172 round merged 2026-06-19 and was never in flight, and a second realignment followed the v1 rework. Also fixes drift found while re-checking fast-agent's resource tool: smart_agent.py is gone (now core/harness_tools.py), get_resource is opt-in via harness_tools (default False, was unconditional), and server_name is now optional - the one surveyed client where the model may omit server identity. Runtime skill loading is still unshipped; #816 remains open. 🦉 Generated with [Claude Code](https://claude.com/claude-code) * docs: track SEP revision 0eb05fe and add mcpkit to the candidates tracker The SEP moved from d7490ec to 0eb05fe (2026-08-05). The delta is editorial for the wire contract -- skills/list, skills/get, and the per-file resources manifest are unchanged -- so d7490ec-pinned implementations stay compatible. Records what it does change: a soft reg-name constraint on the first skill-path segment, the skill root URI fixed as skill://<skill-path> with no trailing slash, whether skills/get carries ttlMs/cacheScope reopened, and normative host obligations in the security section. Adds mcpkit (panyam/mcpkit, Go, v0.3.0) from #118 as a candidate. It implements the pre-v1 index.json catalog shape with per-file digests, so the ecosystem is now split across draft revisions rather than uniformly caught up. 🦉 Generated with [Claude Code](https://claude.com/claude-code) * docs: refine mcpkit entry — deliberate tracking, partial v1 migration Checked mcpkit's issues and PRs rather than inferring alignment from code shape. Its lag is a tracked decision, not drift: - #1185 (merged 2026-08-04) implements origin-tagging and per-origin resolve citing SEP L179/L183/L185 -- the host obligations 0eb05fe made normative -- so it is already on v1 for the security section. #1187 adds a SEP-2640 security/conformance harness as a WG demo. - #780 is an explicit index-schema tracking issue that has absorbed the archives removal and the resources:[{uri,digest}] direction but waits on WG confirmation; its conformance fork pins provenance at 556154c. - The carrier change is still unbooked: nothing references skills/list or skills/get. - Archives are kept as a non-spec extended surface rather than deleted, unlike fast-agent -- a counter-case for whether deferring a feature removes it from the ecosystem. Sharpens the callout accordingly: the draft split runs within an implementation, not only between them, so "which draft does X implement" often has no single answer. 🦉 Generated with [Claude Code](https://claude.com/claude-code)
84 lines
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84 lines
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# Related Work
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## SEPs and Proposals
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| Proposal | Venue | Description |
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| :--- | :--- | :--- |
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| [SEP-2640 (Skills Extension)](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2640) | MCP Spec | This WG's proposed extension: skills served over MCP using the Resources primitive and `skill://` URI scheme ([v1 baseline text](sep-draft-skills-extension.md)) |
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| [PR #2527](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2527) | MCP Spec | Recommend clients expose resource read to models — prerequisite for the resources-based skills approach |
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| [skills.json format proposal](https://github.com/modelcontextprotocol/registry/discussions/895) | MCP Registry | Skills metadata in registry schema |
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| ~~[SEP-2093](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2093)~~ | MCP Spec | ~~Resource Contents Metadata and Capabilities: scoped `resources/list`, per-resource capabilities, `resources/metadata` endpoint~~ — **rejected** ([labeled upstream](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2093)) |
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| ~~[SEP-2076](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2076)~~ | MCP Spec | ~~Agent Skills as a first-class MCP primitive~~ — **closed** (2026-02-24, without merge) |
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> See also [**skills-extension-candidates.md**](skills-extension-candidates.md) for a tracker of MCP servers, dev tools, SDKs, and skills repositories that are candidates for adopting the skills extension.
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## Working Group Member Implementations
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Work by WG leads and active participants that directly implements the group's core patterns: SKILL.md with YAML frontmatter, `skill://` resource URIs, and progressive disclosure via MCP primitives.
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| Implementation | Author | URL | Notes |
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| :--- | :--- | :--- | :--- |
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| skilljack-mcp | Ola Hungerford | [github.com/olaservo/skilljack-mcp](https://github.com/olaservo/skilljack-mcp) | SKILL.md, `skill://` resources, tools, and prompts; progressive disclosure (index→skill→files); file watching for dynamic updates; audience annotations |
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| skills-over-mcp | Keith Groves | [github.com/keithagroves/skills-over-mcp](https://github.com/keithagroves/skills-over-mcp) | SKILL.md, `skill://` resources with progressive disclosure (index→skill→documents); Zod validation against Agent Skills spec |
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| skillsdotnet | Peder HP | [github.com/PederHP/skillsdotnet](https://github.com/PederHP/skillsdotnet) | C# implementation: SKILL.md, `skill://` resources, `load_skill` tool for progressive disclosure, manifest with file hashes; published on NuGet; compatible with FastMCP 3.0 |
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## Alternative Approaches
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Work by WG members and MCP maintainers that explores skills over MCP through different technical approaches than the core SKILL.md / `skill://` pattern.
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| Implementation | Author | Organization | URL | Notes |
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| :--- | :--- | :--- | :--- | :--- |
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| skillful-mcp | Kurtis Van Gent | Google Cloud | [github.com/kurtisvg/skillful-mcp](https://github.com/kurtisvg/skillful-mcp) | Progressive disclosure via 4 lightweight tools (`list_skills`, `use_skill`, `read_resource`, `execute_code`); wraps downstream MCP servers as skills using `mcp.json` config rather than SKILL.md; sandboxed code execution via Monty |
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| Astronomer agents | Kaxil Naik | Astronomer | [github.com/astronomer/agents](https://github.com/astronomer/agents) | Production skills catalog for Apache Airflow (blueprint, migration, warehouse-init); uses SKILL.md frontmatter but distributed via plugin marketplace rather than MCP resources; demonstrates real-world skills adoption at scale |
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| mcpGraph skill | Bob Dickinson | TeamSpark.ai | [github.com/TeamSparkAI/mcpGraph](https://github.com/TeamSparkAI/mcpGraph) | Declarative YAML-based tool orchestration engine (directed graphs of MCP tool calls); includes SKILL.md files as documentation; explores a complementary "no-code composition" approach to skill authoring |
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## Other Community Implementations
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External projects building on skills patterns or integrating skills into frameworks.
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| Implementation | Author | URL | Notes |
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| :--- | :--- | :--- | :--- |
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| FastMCP 3.0 Skills | FastMCP | [gofastmcp.com/servers/providers/skills](https://gofastmcp.com/servers/providers/skills) | Native skills provider ([#2694](https://github.com/jlowin/fastmcp/issues/2694)) |
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| PydanticAI Skills | PydanticAI | [pydantic/pydantic-ai#3780](https://github.com/pydantic/pydantic-ai/pull/3780) | Agent skills with tools-based approach |
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| mcp-execution | bug-ops | [github.com/bug-ops/mcp-execution](https://github.com/bug-ops/mcp-execution) | Compiles MCP servers into skill packages; `--dry-run` preview |
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| mcp-cli | philschmid | [github.com/philschmid/mcp-cli](https://github.com/philschmid/mcp-cli) | Wraps MCP servers as CLI for progressive disclosure |
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| my-cool-proxy | karashiiro | [github.com/karashiiro/my-cool-proxy](https://github.com/karashiiro/my-cool-proxy) | MCP gateway with skills as resources via Lua scripts; result offloading, session persistence (v1.6.x) |
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| NimbleBrain skills repo | NimbleBrain | [github.com/NimbleBrainInc/skills](https://github.com/NimbleBrainInc/skills) | Monorepo with `.skill` artifact format |
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| NimbleBrain registry | NimbleBrain | [registry.nimbletools.ai](https://registry.nimbletools.ai/) | Registry with skill metadata support |
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| NimbleBrain skill:// servers | NimbleBrain | [github.com/NimbleBrainInc](https://github.com/NimbleBrainInc) | skill:// resource colocation examples: [mcp-ipinfo](https://github.com/NimbleBrainInc/mcp-ipinfo), [mcp-webfetch](https://github.com/NimbleBrainInc/mcp-webfetch), [mcp-pdfco](https://github.com/NimbleBrainInc/mcp-pdfco), [mcp-folk](https://github.com/NimbleBrainInc/mcp-folk), [mcp-brave-search](https://github.com/NimbleBrainInc/mcp-brave-search) |
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| Kiro powers directory | Kiro | [github.com/kirodotdev/powers](https://github.com/kirodotdev/powers/) | Plugin directory bundling skills + MCP servers; active catalog (AWS, GCP migration, SAM, etc.) |
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| mcpkit (ext/skills) | Sri Panyam | [github.com/panyam/mcpkit](https://github.com/panyam/mcpkit) | Go SDK, server + host: SKILL.md, `skill://` resources, progressive disclosure (`skill://index.json` catalog + host `load_skill` tool); per-supporting-file digests with verified reads, resource-fetch size + per-server byte budget, `resources/directory/read`; no code-execution surface (enforced by a build-failing test); released in v0.3.0 |
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## Related Ecosystem Work
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Projects that illustrate the problem space or use adjacent patterns.
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| Project | Author | URL | Notes |
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| chrome-devtools-mcp | Google (ChromeDevTools) | [github.com/ChromeDevTools/chrome-devtools-mcp](https://github.com/ChromeDevTools/chrome-devtools-mcp) | Real-world example of the problem: `skills/` folder requires separate install path |
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| Strands Agents MCP server | AWS | [github.com/strands-agents/mcp-server](https://github.com/strands-agents/mcp-server/) | Docs-as-MCP: TF-IDF search + doc fetch |
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| AWS MCP server | AWS | [docs.aws.amazon.com/aws-mcp/…](https://docs.aws.amazon.com/aws-mcp/latest/userguide/understanding-mcp-server-tools.html) | `retrieve_agent_sop` (skills) + `call_aws` (tool) |
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## Specifications and Standards
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- **Agent Skills Standard:** [agentskills.io](https://agentskills.io/)
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- **Agent Skills Discovery RFC v0.2.0** (Matt Silverlock / Cloudflare): [github.com/cloudflare/agent-skills-discovery-rfc](https://github.com/cloudflare/agent-skills-discovery-rfc) — Domain-level skill discovery using `/.well-known/agent-skills/` (RFC 8615). Defines `index.json` with progressive disclosure, `skill-md` and `archive` distribution types, `$schema` versioning, SHA-256 content integrity, and archive safety requirements. Complementary to MCP-level discovery: `.well-known` answers "what skills does this domain publish?" while MCP answers "how does the agent consume them at runtime?"
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- **Skill dependency declaration:** [agentskills/agentskills#110](https://github.com/agentskills/agentskills/issues/110) — Discusses how skills should declare their tool/server dependencies
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- **Apache Airflow AIP-91** (MCP integration): [cwiki.apache.org/…/AIP-91+-+MCP](https://cwiki.apache.org/confluence/display/AIRFLOW/AIP-91+-+MCP)
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## Integrity, Content Addressing, and Attestation
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Related work on establishing and verifying the integrity, authenticity, and provenance of skill resources.
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- **skill-set format (draft)** (Harry Martin / flocker.md): [skill-set.md](https://skill-set.md/) — Transport-agnostic manifest specification and CLI for named, versioned collections of skills assembled from disparate sources. Defines deterministic whole-skill content hashes and set-level roll-ups, lockfiles, receipt-time content verification, and optional out-of-band URL-fragment pins. Complementary to SEP-2640: provides prior art for deriving a single content address from a complete `{uri, digest}` resource set and for future whole-skill or multi-skill attestations. See the [reference directory](https://skill-sets.md/sets/skill-authoring/) for an immutable example.
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## Background Reading
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- **Anthropic's guidance on progressive disclosure:** [Equipping agents for the real world with agent skills](https://www.anthropic.com/engineering/equipping-agents-for-the-real-world-with-agent-skills)
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- **"MCP and Skills: Why Not Both?"** (Kurtis Van Gent): [kvg.dev/posts/20260125-skills-and-mcp/](https://kvg.dev/posts/20260125-skills-and-mcp/) — Frames MCP (connectivity) and Skills (context saturation) as complementary; discusses hybrid approaches
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- **"Skills Over MCP"** (Angie Jones, Agentic AI Foundation): [aaif.io/blog/skills-over-mcp/](https://aaif.io/blog/skills-over-mcp/) — "Ship the manual with the product": bundle Agent Skills with MCP servers so agents get both tools and instructional guidance. Describes the working group's proposal (SEP-2640) — `skill://` resources, a `skill://index.json` catalog for lightweight discovery, and progressive disclosure of full instructions on demand
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- **"Progressive Discovery in MCP, Part 2"** (Sam Morrow, GitHub MCP Server maintainer): [sam-morrow.com/blog/progressive-discovery-in-mcp-part-2](https://sam-morrow.com/blog/progressive-discovery-in-mcp-part-2) — Advocates skills-based progressive discovery to solve tool bloat: `skill://` resources, deferred tool loading via provider mechanisms (Anthropic `tool_reference`, OpenAI `defer_loading`), and the `io.modelcontextprotocol/tools` metadata namespace. Grounded in lessons from GitHub's MCP Server (100+ tools, 12M weekly calls)
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- **Conceptual spec visualization** (Keith Groves): [enact-465fb1fc.mintlify.app/specification/draft/server/skills](https://enact-465fb1fc.mintlify.app/specification/draft/server/skills) — "What if" exploration
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- **llms.txt convention:** [llmstxt.org](https://llmstxt.org/) — Convention for making documentation LLM-accessible; used by [MCPDoc](https://github.com/langchain-ai/mcpdoc) in a way similar to how skills work
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- **AWS Agent SOPs:** [docs.aws.amazon.com/…/agent-sops](https://docs.aws.amazon.com/aws-mcp/latest/userguide/agent-sops.html) — Pre-built operational workflows as skill-like guidance
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- **Video background:** [youtube.com/watch?v=CEvIs9y1uog](https://www.youtube.com/watch?v=CEvIs9y1uog)
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