AGENTS.md vs agents.txt
They answer different questions: AGENTS.md is a step 4 (Read) standard, agents.txt step 1 (Discover), so they are not substitutes.
| AGENTS.md | agents.txt | |
|---|---|---|
| Lifecycle step | 4 Read: Give me the content | 1 Discover: What is here, and where? |
| Answers | What build, test, and convention instructions should a coding agent follow in this repository? | Which agent-facing protocols (payments, auth, MCP, skills, A2A) does this site speak, and where? |
| Governed by | Agentic AI Foundation (AAIF), a Linux Foundation project | 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 (issuer's words) | "An open format... regardless of which coding agent you use"; explicitly not proprietary to any one tool | "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 | living | idea |
| Version | current site guidance (living document) (2026-09) | agents-txt.com: v1.0; competing proposals carry no shared version |
| Form / transport | well-known file | well-known file |
| Found at | AGENTS.md | /agents.txt (well-known root path per all identified proposals; one proposal also allows /.well-known/agents.txt) |
| Adoption | claimed — agents.md (site claims over 60,000 AGENTS.md files across open-source GitHub repositories, via a path:AGENTS.md NOT is:fork NOT is:archived code search) | unmeasured |
| Evidence | 2 reported, 1 verified | 3 verified, 1 reported |
| Primary use case | Serve readable content to agents | Let agents discover my API or service |
| Last verified | 2026-10-19 (current) | 2026-10-16 (current) |
| Specification | https://agents.md | https://agents-txt.com/spec |
When to use which
- Choose AGENTS.md when your question is “What build, test, and convention instructions should a coding agent follow in this repository?” and you accept its maturity: phase living, adoption claimed (agents.md (site claims over 60,000 AGENTS.md files across open-source GitHub repositories, via a path:AGENTS.md NOT is:fork NOT is:archived code search)).
- Choose agents.txt when your question is “Which agent-facing protocols (payments, auth, MCP, skills, A2A) does this site speak, and where?” and you accept its maturity: phase idea, adoption unmeasured.
Read the full articles
- AGENTS.md: What build, test, and convention instructions should a coding agent follow in this repository?
- agents.txt: Which agent-facing protocols (payments, auth, MCP, skills, A2A) does this site speak, and where?