# agents.txt

[1 · Discover](/category/discover/)

| agents.txt |
| --- |
| Category | [Discover](/category/discover/) |
| Governed by | None; at least three non-converging proposals (agents-txt.com, kaylacar/agents-txt, agentstxt.dev) each self-describe as "the" agents.txt standard, with no shared maintainer or reconciliation process found |
| Status | "An open standard proposal for declaring what AI agents can do on a website" (kaylacar/agents-txt); a Mastercard developer-documentation page independently characterizes the space as "IETF draft expired ... fragmented landscape with 11+ competing proposals ... no ratified standard" |
| Phase | idea |
| Implementation | prototype |
| Adoption | unmeasured |
| Version | agents-txt.com: v1.0; competing proposals carry no shared version |
| Specification | [https://agents-txt.com/spec](https://agents-txt.com/spec) |
| Found at | /agents.txt (well-known root path per all identified proposals; one proposal also allows /.well-known/agents.txt) |
| Acronym collisions | Multiple unrelated, mutually incompatible specifications share the "agents.txt" name (see dispute): agents-txt.com's v1.0 protocol-declaration format, kaylacar/agents-txt's IETF-draft capability-declaration proposal, agentstxt.dev (a separate proposal whose IETF draft expired 2026-04-10), and the ad hoc allow/rate-limit format described in the arXiv paper 'Towards an Agent-First Web' |
| Last checked | 2026-09-06 |

[Discover](/category/discover/) Moved from the Read step to Discover. agents.txt is not one specification but a name shared by at least four non-converging proposals for a site-root text file that declares which agent-facing protocols (payments, auth, MCP endpoints, Skills, A2A) a site supports and where to find them [[1]](#ref-1)[[2]](#ref-2)[[3]](#ref-3)[[4]](#ref-4). It is filed here under "Discover" (what is here, and where?) rather than "Read", since every version found declares protocol/capability presence and location, not page content, and one variant (agents-txt.com) explicitly frames itself as complementary to A2A's AgentCard discovery and RFC 9727's API Catalog [[1]](#ref-1).

## Overview
What it is (per the most detailed version found, agents-txt.com's v1.0): a plain-text file at the site root listing supported protocols, e.g. Protocols: x402, mpp, with directives for pointing agents at an A2A AgentCard, an MCP endpoint, or other machine-readable capability declarations [[1]](#ref-1). A second, independently maintained proposal (kaylacar/agents-txt) describes a similar but not identical capability-declaration format and claims IANA filing (#72/#73, "under review") and an active IETF Internet-Draft [[2]](#ref-2). A third effort, agentstxt.dev, is reported by a Mastercard developer-documentation page to have had its IETF draft expire on 2026-04-10, with that same source describing "a fragmented landscape with 11+ competing proposals ... no ratified standard" [[3]](#ref-3). A fourth, academic proposal in the arXiv paper "Towards an Agent-First Web" defines yet another agents.txt grammar (INI-style [agent-class] blocks with allow/rate-limit/content-format fields) without referencing any of the other three [[4]](#ref-4).

It solves, in principle, the problem of an agent needing to discover a site's supported protocols in one request rather than probing each well-known path individually — a genuine gap, since A2A, MCP, x402, and other protocols each define their own discovery convention but nothing ties them together at a single site level.

It does not currently solve that problem in practice, because there is no single agents.txt to fetch: an agent cannot know, without trying multiple grammars, which of at least four incompatible conventions (if any) a given site implements. None of the identified efforts has IETF ratification, and the one with the most third-party visibility (agentstxt.dev) had its own draft lapse.

Current state, as of this verification (September 2026): earliest dated public artifact found is the kaylacar/agents-txt GitHub repository, created 2026-02-22 and last updated 2026-07-18 [[2]](#ref-2); agents-txt.com presents a v1.0 spec text with no stated publication date [[1]](#ref-1); the Mastercard reference page's fragmentation characterization is dated to 2026 without a specific day [[3]](#ref-3). No implementation count, adopter list, or resolution among the competing proposals was found.

What is disputed: everything about precedence, authorship, and which (if any) proposal will consolidate the space. This record should be treated as thin pending a resolution or a dominant implementation emerging.

## Discovery and probe

Fixed filename at the site root · /agents.txt (well-known root path per all identified proposals; one proposal also allows /.well-known/agents.txt)

```
GET {origin}/agents.txt
parse:     200 response with a text/plain body listing supported protocols (e.g. `Protocols: x402, mpp`) or per-agent directives, per whichever competing grammar the site chose to implement
on absent: No agents.txt at the site root under any of the competing conventions; given the fragmentation, absence is a weak signal either way
```

Live check run by [the MCP probe](/mcp/server-card): GET /agents.txt. Competing agents.txt grammars share only the path; a non-empty file is the signal.

```
{
 "path": "/agents.txt",
 "expect": {
  "text_match": "\\S"
 },
 "note": "Competing agents.txt grammars share only the path; a non-empty file is the signal."
}
```

## History
- 2026-09-06 — new record added during read-step verification; reclassified to the discover step after finding the name covers multiple non-converging, competing specifications

## Instances

- [Mnemom](https://www.mnemom.ai/agents.txt) · Observed 2026-08-29 · business
- [DreamHost](https://blakecrosley.com/blog/agents-txt-not-access-control) · Observed 2026-05-18 · business
- [agents-txt/agents-txt (GitHub project)](https://trendshift.io/repositories/32945) · Observed 2026-05-13 · service
- [MetricSpot](https://metricspot.com/docs/agents-txt/) · Observed 2026-05-11 · service

Every instance with its source is listed on the [instances page](/instances/).

## See also

- Not to be confused with: Multiple unrelated, mutually incompatible specifications share the "agents.txt" name (see dispute): agents-txt.com's v1.0 protocol-declaration format, kaylacar/agents-txt's IETF-draft capability-declaration proposal, agentstxt.dev (a separate proposal whose IETF draft expired 2026-04-10), and the ad hoc allow/rate-limit format described in the arXiv paper 'Towards an Agent-First Web'

## References

- agents-txt.com publishes a v1.0 'agents.txt Standard' spec: a text file at the site root declaring supported protocols (e.g. x402, mpp), with explicit sections relating it to A2A's AgentCard discovery and to RFC 9727's API Catalog — [https://agents-txt.com/spec](https://agents-txt.com/spec) (2026) VERIFIED
- A separate GitHub proposal, kaylacar/agents-txt, describes itself as an open standard proposal for AI-agent capability declaration via a well-known URI, with IANA numbers #72/#73 'filed, under review' and an IETF Internet-Draft on Datatracker; the repository was created 2026-02-22 and last updated 2026-07-18 — [https://github.com/kaylacar/agents-txt](https://github.com/kaylacar/agents-txt) (2026-07-18) VERIFIED
- A Mastercard merchant-developer reference page lists agents.txt (at agentstxt.dev, a third distinct effort) as an 'Emerging Standard (Draft)' whose IETF draft expired 2026-04-10, describing 'a fragmented landscape with 11+ competing proposals (agent-manifest.txt, agents-brief.txt, etc.)' and 'no ratified standard' (may require login: HTTP 401 on one check and 200 on another, 2026-09-06) — [https://developer.mastercard.com/merchant-cloud/documentation/tutorials-and-guides/agentic-commerce-guide/24/](https://developer.mastercard.com/merchant-cloud/documentation/tutorials-and-guides/agentic-commerce-guide/24/) (2026) REPORTED
- An arXiv paper, 'Towards an Agent-First Web', independently proposes its own agents.txt grammar (INI-style allow/rate-limit/content-format blocks per agent class) served at /.well-known/agents.txt, distinct from the other three — [https://arxiv.org/html/2606.19116v1](https://arxiv.org/html/2606.19116v1) (2026) VERIFIED

Disputed: "agents.txt" names at least four non-converging, mutually incompatible proposals (agents-txt.com's v1.0, kaylacar/agents-txt's IETF-draft capability format, agentstxt.dev's expired-draft format, and an academic paper's own INI-style grammar), none of which has become a ratified or dominant standard.

[JSON](/data/protocols/agents-txt.json) · [Markdown](/protocols/agents-txt/index.md)