A flat index of every endpoint, grouped by tag or resource, with one-line summaries.
llms.txt for API teams
How to write llms.txt for an API.
An API's llms.txt is the file coding agents read before they touch the SDK. Get it right and Claude / Cursor / Codex wire up calls correctly on the first try. Get it wrong and they hallucinate endpoints.
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01Details
What coding agents need from llms.txt
Links to per-endpoint Markdown reference pages (not HTML) so the agent can read full request/response shape without parsing layout chrome.
Authentication summary up front so the agent picks the right auth header on the first call.
A Quickstart section showing one canonical request/response pair per language the SDK supports.
02Details
The five sections that work for API docs
## Quickstart — link to the getting-started Markdown page; one snippet each in TypeScript and Python.
## Authentication — bearer / OAuth / API-key flow in three sentences plus a link to the auth reference.
## API reference — one link per endpoint group (resource or tag), each pointing to the .md reference page.
## SDKs — links to the canonical SDK install + import paths per language.
## Optional — changelog, migration notes, deep dives, design rationale.
03Details
What to surface vs hide
Surface every public endpoint. Agents that miss endpoints will invent them.
Surface error codes and their meanings. The most common agent failure mode is misreading 4xx → silent retry → infinite loop.
Hide deprecated endpoints under Optional with a clear note — agents that read Optional first will avoid them.
Hide marketing pages entirely from the main sections; put them under Optional or leave them out.
04Outputs
Generated from OpenAPI vs hand-written
Hand-written llms.txt drifts the moment the API changes. Two releases in and the file is wrong.
Generated llms.txt regenerates with every spec push — the contents match production.
Bloom generates llms.txt from OpenAPI by default: endpoints grouped by tag, per-endpoint .md pages, auth summary built from the spec's securitySchemes, examples pulled from spec examples.
If you generate elsewhere (Mintlify, Fern, ReadMe), check whether per-page Markdown ships alongside the file — the links break if not.
05Checks
Six-point checklist before you publish
H1 with API name + version (e.g. # Acme API v2026-05-01).
Blockquote with the one-line product description.
Quickstart linking to .md getting-started.
Auth section summarised in three sentences.
API reference grouped by resource, every link a .md.
Optional section with changelog + deprecations.