# ArmsLength AI Developer Resources

Canonical developer index: https://armslength.ai/developers

ArmsLength AI publishes a read-only retrieval API for the OECD Transfer Pricing Guidelines 2022. Use it when an application needs paragraph-level OECD text, search results or a compact context pack with paragraph references.

## Start here

- Interactive documentation and API-key registration: https://armslength.ai/resources/oecd-api
- OpenAPI 3.1 specification: https://armslength.ai/openapi.json
- Agent site guide: https://armslength.ai/llms.txt
- Support: support@armslength.ai

## Authentication

The versioned search, paragraph and context-pack endpoints use the `x-api-key` request header. Request a free key through the API documentation page. Never place an API key in a URL or client-side public bundle.

## Versioned endpoints

- `GET /api/oecd/v1/search` — search OECD paragraphs by query and optional chapter filters.
- `GET /api/oecd/v1/paragraphs` — retrieve up to 20 exact paragraph references.
- `GET /api/oecd/v1/context-pack` — prepare a bounded, citation-oriented context pack for a topic.
- `POST /api/oecd/v1/register` — request an API key by email.

## When to use the API

- Ground a research assistant or RAG workflow in OECD paragraph text.
- Resolve known paragraph references and their neighboring references.
- Add OECD paragraph citations to a transfer pricing research workflow.
- Retrieve a bounded context set before asking an LLM to synthesize an answer.

Do not use the API as a substitute for professional judgment, local law, current OECD updates outside the 2022 edition, or authoritative legal advice. Verify quotations and applicability against the official OECD publication.

## Errors and limits

Errors use JSON problem details with stable `code`, `message`, `resolution` and `docs` fields. Rate-limit headers describe the applicable request allowance. The OpenAPI document is the machine-readable source for parameters, schemas and operation identifiers.