# WebMCP vs agents.json

The map lists them as complementary: sites and agents commonly implement both.

[5 Act](/category/act/) [WebMCP](/protocols/webmcp/) · [5 Act](/category/act/) [agents.json](/protocols/agents-json/)

|  | [WebMCP](/protocols/webmcp/) | [agents.json](/protocols/agents-json/) |
| --- | --- | --- |
| Lifecycle step | 5 Act: Do something for me | 5 Act: Do something for me |
| Answers | What JavaScript tools can a web page register so an in-browser AI agent can call them directly instead of scraping the DOM? | How does an agent learn which multi-step API call sequences ("flows") a service supports, on top of its raw OpenAPI surface? |
| Governed by | W3C Web Machine Learning Community Group; editors are Brandon Walderman (Microsoft), Khushal Sagar (Google), Dominic Farolino (Google) | Wildcard AI; single company controls the spec and the reference "Wildcard Bridge" runtime and maintains a discretionary registry of published files |
| Status (issuer's words) | Draft Community Group Report, dated 4 September 2026; explicitly "not a W3C Standard nor on the W3C Standards Track" | Dormant: last push 2025-08-21, version 0.1.0 |
| Version | Draft Community Group Report, 4 September 2026 (2026-09-04) | 0.1.0 (2025-03) |
| Form / transport | browser API | well-known file |
| Found at | none — a client or agent must load the page itself to see whether it registers WebMCP tools; this is a stated limitation of the API ("Clients and browsers must visit a site directly to know if it has callable tools") | /.well-known/agents.json (proposed; not mandatory, per the spec's own FAQ) |
| Implementation | prototype | prototype |
| Evidence | 2 verified | 4 verified, 2 reported |
| Primary use case | Let agents act on my website | Let agents discover my API or service |
| Last verified | 2026-10-23 (current) | 2026-10-23 (current) |
| Specification | [https://webmachinelearning.github.io/webmcp/](https://webmachinelearning.github.io/webmcp/) | [https://github.com/wild-card-ai/agents-json](https://github.com/wild-card-ai/agents-json) |

## When to use which

- Choose WebMCP when your question is “What JavaScript tools can a web page register so an in-browser AI agent can call them directly instead of scraping the DOM?” and you accept its maturity: status "Draft Community Group Report, dated 4 September 2026; explicitly "not a W3C Standard nor on the W3C Standards Track"", implementation prototype.
- Choose agents.json when your question is “How does an agent learn which multi-step API call sequences ("flows") a service supports, on top of its raw OpenAPI surface?” and you accept its maturity: status "Dormant: last push 2025-08-21, version 0.1.0", implementation prototype. It is no longer maintained; prefer its successor.

Guidance is derived from the two records (question, status, implementation, prerequisites, pairings), not from opinion. Each record's page carries its numbered references.

## Read the full articles

- [WebMCP](/protocols/webmcp/): What JavaScript tools can a web page register so an in-browser AI agent can call them directly instead of scraping the DOM?
- [agents.json](/protocols/agents-json/): How does an agent learn which multi-step API call sequences ("flows") a service supports, on top of its raw OpenAPI surface?

Ask the MCP server to compare any two: the compare-protocols prompt, or get on both ids. [Connect](/connect/).

[webmcp.json](/data/protocols/webmcp.json) · [agents-json.json](/data/protocols/agents-json.json) · [Markdown](/compare/webmcp-vs-agents-json/index.md)