---
title: "WebMCP vs agents.json | Agent MCP Directory"
description: "WebMCP vs agents.json: one sourced difference and a verdict for product engineers, platform leads and agent builders. Read 4 November 2026."
canonical: https://agentmcpdirectory.com/compare/webmcp-vs-agents-json
site: "Agent MCP Directory"
last_updated: 2026-11-05
section: "Head-to-heads"
---

# WebMCP vs agents.json | Agent MCP Directory

> WebMCP vs agents.json: one sourced difference and a verdict for product engineers, platform leads and agent builders. Read 4 November 2026.

Source: https://agentmcpdirectory.com/compare/webmcp-vs-agents-json
Site: Agent MCP Directory
Last reviewed: 2026-11-05

# WebMCP vs agents.json

Product engineer: agents.json documents an API; WebMCP wraps page actions. Developer-platform lead: agents.json is at 0.1.0; WebMCP has browser vendors behind it. Agent builder: Neither is required by MCP clients today. WebMCP exposes JavaScript tools in the page at run time; agents.json is a static OpenAPI-based file at /.well-known/agents.json describing API flows.

## The sourced difference

WebMCP exposes JavaScript tools in the page at run time; agents.json is a static OpenAPI-based file at /.well-known/agents.json describing API flows. (WebMCP: [webmachinelearning/webmcp](https://github.com/webmachinelearning/webmcp), read 5 November 2026; agents.json: [wild-card-ai/agents-json](https://github.com/wild-card-ai/agents-json), observed on 4 November 2026 and [wild-card-ai/agents-json](https://github.com/wild-card-ai/agents-json), read 5 November 2026)

## Verdicts by reader

| Reader | Verdict |
| --- | --- |
| Product engineer | agents.json documents an API; WebMCP wraps page actions. |
| Developer-platform lead | agents.json is at 0.1.0; WebMCP has browser vendors behind it. |
| Agent builder | Neither is required by MCP clients today. |

## Side by side

| Aspect | WebMCP | agents.json |
| --- | --- | --- |
| Maintainer | W3C Web Machine Learning Community Group (editors from Microsoft and Google) | Wildcard AI (started the project); maintainers listed in MAINTAINERS.md |
| What it is | A browser API that lets a page register JavaScript functions as tools, with descriptions and schemas, that an in-browser agent can call. | An OpenAPI-based contract that describes flows (sequences of API calls) and links between actions so agents can call an API correctly. |
| Status and version | Draft specification; Chrome and Edge test it in an origin trial, Brave behind a flag, no Firefox or Safari implementation (nekuda FAQ, October 2026). | Version 0.1.0, MIT licence; proposed location /.well-known/agents.json. |
| What it does not do | Does not work without a browser agent that reads the page; does not replace a server-side MCP endpoint; the declarative form-based API is only being explored. | Does not define transport or auth beyond OpenAPI; not referenced by the MCP spec. |

Read the full entries: [WebMCP](https://agentmcpdirectory.com/standards/webmcp/) and [agents.json](https://agentmcpdirectory.com/standards/agents-json/).

## Seen in the shared crawl

The shared crawl looks for WebMCP in the initial HTML of each home page. It found a WebMCP hint on 25 of 7,545 home pages in the Tranco top 10,000 and on 59 of 3,393 on Ora's leaderboard.

| Path | Top 10,000 found | Ora leaderboard found |
| --- | --- | --- |
| /agents.json | 0 of 7,485 (0%) | 0 of 3,366 (0%) |

A path counts only when the answer is the right kind of document. Many sites answer these paths with an ordinary web page, which is not counted. See [the census](https://agentmcpdirectory.com/census/).

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/compare/webmcp-vs-agents-json/index.md)

## Sources

-   [webmachinelearning/webmcp](https://github.com/webmachinelearning/webmcp), read 5 November 2026
-   [wild-card-ai/agents-json](https://github.com/wild-card-ai/agents-json), read 4 November 2026 (Fact noted from the github.com page on 4 November 2026.)

Last reviewed 5 November 2026