Standards for the act layer
Eight reference entries for the standards an agent uses to act: MCP, WebMCP, A2A, agents.json, NLWeb, Agent Skills, OpenAPI and the command line. Each states what it is, who maintains it, its version and what it does not do, with dated sources.
| Standard | Maintainer | Status and version |
|---|---|---|
| Model Context Protocol | MCP maintainers under the Agentic AI Foundation | Current revision 2026-07-28 (released 28 Jul 2026); prior revision 2025-11-25. Registry in preview with API v0.1 frozen since 24 Oct 2025. |
| WebMCP | W3C Web Machine Learning Community Group (editors from Microsoft and Google) | Draft specification; Chrome and Edge test it in an origin trial, Brave behind a flag, no Firefox or Safari implementation (nekuda FAQ, October 2026). |
| Agent2Agent | A2A project, Growth Stage project at the Agentic AI Foundation (Linux Foundation-directed) | Specification 1.0.0 is the latest release; joined the Agentic AI Foundation on 27 Aug 2026. |
| agents.json | Wildcard AI (started the project); maintainers listed in MAINTAINERS.md | Version 0.1.0, MIT licence; proposed location /.well-known/agents.json. |
| NLWeb | Microsoft (repository nlweb-ai/NLWeb) | Active open-source project, MIT licence, about 6.3k stars; no tagged releases shown on 4 Nov 2026. |
| Agent Skills | agentskills.io open standard (originated at Anthropic) | Open format with a published specification at agentskills.io; adopted across many agent clients. |
| OpenAPI as an agent surface | OpenAPI Initiative (spec); each vendor for its own file | OpenAPI 3.x in wide use; agents.json and Kong's AI MCP Server build on it. |
| CLIs as an agent surface | Each vendor | Common practice; AgentReady.org (launched 19 Oct 2026) lists "an MCP server or a CLI, at least one" as a MUST for the act layer. |
These eight entries are reference pages. They are not scored, because a specification is not a product; the products that host and list MCP servers are scored on the hosts page.