--- title: "MCP, A2A and WebMCP by job | Agent MCP Directory" description: "MCP, A2A and WebMCP by job. Choose the surface by the job: tools on a server, delegation to another agent, or actions on a live page." canonical: https://agentmcpdirectory.com/guides/mcp-vs-a2a-vs-webmcp site: "Agent MCP Directory" last_updated: 2026-11-04 section: "Guides" --- # MCP, A2A and WebMCP by job | Agent MCP Directory > MCP, A2A and WebMCP by job. Choose the surface by the job: tools on a server, delegation to another agent, or actions on a live page. Source: https://agentmcpdirectory.com/guides/mcp-vs-a2a-vs-webmcp Site: Agent MCP Directory Last reviewed: 2026-11-04 # MCP, A2A and WebMCP by job Choose the surface by the job: tools on a server, delegation to another agent, or actions on a live page. A table below sets the three side by side. Use MCP for tools and data behind an API, A2A when another agent should take a task and WebMCP when a user is on the page and the agent acts there. ## Steps 1. Tools and data behind an API: MCP. 2. Another agent should take a task: A2A Agent Card. 3. A user is on the page and the agent acts there: WebMCP. ## What the sources say - MCP standard transports are stdio and Streamable HTTP. ([modelcontextprotocol.io](https://modelcontextprotocol.io/specification/2026-07-28/basic/transports), read 4 November 2026) - A2A 1.0.0 binds to JSON-RPC, gRPC or HTTP+JSON and publishes /.well-known/agent-card.json. ([a2a-protocol.org](https://a2a-protocol.org/latest/specification/), read 4 November 2026) - WebMCP tools live in the page and are reached through document.modelContext. ([github.com](https://github.com/webmachinelearning/webmcp), read 4 November 2026) - MCP and A2A are both projects of the Agentic AI Foundation since A2A joined on 27 Aug 2026. ([a2a-protocol.org](https://a2a-protocol.org/latest/blog/2026/08/27/a-new-chapter-for-a2a-joining-the-agentic-ai-foundation/), dated 27 August 2026, read 4 November 2026) - Kong AI Gateway reports OpenTelemetry metrics for AI, MCP and A2A traffic side by side. ([developer.konghq.com](https://developer.konghq.com/ai-gateway/), read 4 November 2026) ## The three side by side | Standard | What it is | Status and version | | --- | --- | --- | | Model Context Protocol | A JSON-RPC 2.0 protocol between hosts, clients and servers; servers offer tools, resources and prompts, and clients may offer elicitation. | 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. | | Agent2Agent | A protocol for agents to discover each other through an Agent Card and exchange tasks and messages. | Specification 1.0.0 is the latest release; joined the Agentic AI Foundation on 27 Aug 2026. | | WebMCP | A browser API that lets a page register JavaScript functions as tools, with descriptions and schemas, that an in-browser agent can call. | Draft specification; Chrome and Edge test it in an origin trial, Brave behind a flag, no Firefox or Safari implementation (nekuda FAQ, October 2026). | Pairwise: [MCP vs A2A](https://agentmcpdirectory.com/compare/mcp-vs-a2a/), [MCP vs WebMCP](https://agentmcpdirectory.com/compare/mcp-vs-webmcp/) and [WebMCP vs agents.json](https://agentmcpdirectory.com/compare/webmcp-vs-agents-json/). Edition 4 November 2026 Method [How rows are verified](https://agentmcpdirectory.com/method/) Data [CSV and JSON](https://agentmcpdirectory.com/data/) Markdown [This page as markdown](https://agentmcpdirectory.com/guides/mcp-vs-a2a-vs-webmcp/index.md) ## Sources - [MCP, A2A and WebMCP by job](https://modelcontextprotocol.io/specification/2026-07-28/basic/transports), read 4 November 2026 - [a2a-protocol.org/latest/specification](https://a2a-protocol.org/latest/specification/), read 4 November 2026 - [github.com/webmachinelearning/webmcp](https://github.com/webmachinelearning/webmcp), read 4 November 2026 - [a2a-protocol.org/latest/blog/2026/08/27/a-new-chapter-for-a2a-joining-the-agentic-ai-foundation](https://a2a-protocol.org/latest/blog/2026/08/27/a-new-chapter-for-a2a-joining-the-agentic-ai-foundation/), read 4 November 2026 - [developer.konghq.com/ai-gateway](https://developer.konghq.com/ai-gateway/), read 4 November 2026 Last reviewed 4 November 2026