§5.3 · COMPARE · LAST REVIEWED SEPTEMBER 2026
llms.txt vs agents.json: content map or API contract?
Both are files you publish for agents. They answer different questions.
Agent Readiness Compare editors · Spec status checked September 2026
Answer
llms.txt is a markdown file at /llms.txt that tells a language model what your site is and which pages to read. agents.json is a JSON file, proposed at /.well-known/agents.json, that tells an agent which API calls to chain to reach an outcome, built on OpenAPI. Publish llms.txt for almost any site; add agents.json if agents should complete multi-step tasks through your API.
On this page
1.How do they differ?
| Attribute | llms.txt | agents.json |
|---|---|---|
| Answers | What is this site and where is the good content? | Which calls, in which order, reach this outcome? |
| Format | Markdown: required H1, summary blockquote, H2 link lists | JSON built on OpenAPI, with flows and links |
| Location | /llms.txt (or a sub-path such as /docs/llms.txt) | /.well-known/agents.json |
| Maintainer | Proposed by Jeremy Howard (llmstxt.org) | Wildcard AI (GitHub, MIT license) |
| Status | Community proposal | Open specification, version 0.1.0 |
| Layer | Discover, Read | Act |
| Effort | Minutes to an hour | Depends on your API; needs an OpenAPI file first |
2.Which should you publish first?
llms.txt. It is cheap and helps any agent that reads it. agents.json only pays off when you have an API and tasks that span several calls.
3.Do they overlap with other files?
Yes, partly. robots.txt controls crawling, not content. An MCP server can expose the same tasks as agents.json flows as callable tools. An A2A Agent Card describes an agent, not an API or a site.
Frequently asked questions
Can I publish both llms.txt and agents.json?
Yes. They do not conflict.
Does llms.txt replace a sitemap?
No. A sitemap lists every URL for crawlers. llms.txt is a short, curated set of the most useful pages with descriptions.
Source: llmstxt.org · github.com/wild-card-ai/agents-json · Reviewed Sep 2026