# Resend — API Agent Score

> Score: 85/100 (Grade: A) | Domain: resend.com | Rubric: 1.0.0 | Checked: July 24, 2026

Resend scored 85/100 (A), classified "ai-ready".

[View full report](https://www.postman.com/ai/ai-ready-apis/company/resend)
[All organizations](https://www.postman.com/ai/ai-ready-apis/llms.txt)

## Summary

- Overall: 85/100 (A)
- Classification: ai-ready

## Category Scores

- API Design: 92/100 (A+)
- Developer Experience: 75/100 (B)
- Agent Discovery: 97/100 (A+)
- Agent Understanding: 68/100 (C)
- Agent Usability: 92/100 (A+)

## Check Results

### API Design

- [pass] Auth declared & discoverable — Authentication required (global or on every operation). Investigated: spec 100%, docs 100%.
- [warn] Schema coverage & depth — 6 of 249 public signatures use loose types (anyTypeRatio=0.024). Investigated: sdk 90%, spec 67%.
- [warn] Machine-readable, versioned contract — info.version="1.5.0" set but no versioning scheme (URL / header / media type) detected. Investigated: spec 75%, docs 50%.
- [pass] Security & governance hygiene — No credential-shaped strings detected in spec. Investigated: spec 100%, wellknown 50%.
- [pass] Example coverage — README is present and includes a runnable quickstart. Investigated: sdk 100%, spec 0%, docs 0%.

### Developer Experience

- [pass] Self-service developer portal — Self-service signup at https://resend.com/signup; free tier / sandbox documented. Investigated: docs 100%.
- [pass] Description completeness — 92% of operations + parameters have substantive descriptions. Investigated: spec 100%, sdk 94%.
- [pass] Changelog published — changelog documented in the docs site at https://resend.com/changelog. Investigated: spec 100%, docs 100%, sdk 100%.
- [warn] Quickstart present — Quickstart page reachable (1 variants scanned starting at https://resend.com/signup) but no runnable code sample detected in HTML or .md variant. Investigated: docs 50%.
- [fail] Code samples in docs — No detectable code samples across 20 sampled docs pages. Investigated: docs 0%.

### Agent Discovery

- [pass] llms.txt present, valid & comprehensive — llms.txt found at 2 locations; using https://resend.com/docs/llms.txt as canonical. Investigated: docs 100%, sdk 0%.
- [pass] Docs reachable, not hard auth-gated — All 1 pages are publicly accessible. Investigated: docs 100%.
- [pass] Registry & SDK presence — Indexed on Context7 (websites/resend, 5371 snippets). Investigated: docs 100%, cli 100%, sdk 92%, mcp 0%, wellknown 0%.
- [warn] Crawlable / AEO — Sitemap present (11 entries) but carries no lastmod values. Investigated: wellknown 75%.

### Agent Understanding

- [pass] Machine-readable errors (RFC 9457) — error codes documented in the docs site at https://resend.com/docs/api-reference/errors. Investigated: spec 100%, docs 100%, sdk 100%.
- [pass] Agent-navigable, token-efficient docs — All 1 pages contain server-rendered content. Investigated: docs 100%.
- [pass] Docs structured data — JSON-LD Article markup on 20/20 assessed pages (100%) with dateModified present. Investigated: docs 100%.
- [warn] Description consistency across surfaces — Mean pairwise description similarity across 2 surfaces (docs, sdk) is 8% (threshold 35% for full credit).
- [fail] Operation purpose clarity — 0% of operations are agent-inferable. Investigated: spec 0%.
- [fail] Agent instructions file (AGENTS.md) — No AGENTS.md at the site root or /.well-known/. Investigated: wellknown 0%.

### Agent Usability

- [pass] Idempotency documented — idempotency documented in the docs site at https://resend.com/docs/dashboard/emails/idempotency-keys. Investigated: spec 100%, docs 100%, sdk 100%.
- [pass] Rate-limit signaling — rate-limit behavior documented in the docs site at https://resend.com/docs/api-reference/rate-limit. Investigated: spec 100%, docs 100%.
- [pass] Pagination documented & consistent — Pagination params detected on 23 list endpoint(s). Investigated: spec 100%, docs 100%, sdk 0%.
- [pass] Sandbox separation — Sandbox environments are exposed (sandbox). Investigated: sdk 100%, spec 0%, docs 0%.
- [fail] Runnable collection with test scripts — No public Postman workspace discovered for the org. Investigated: platform 0%.

## Executive Summary

Resend's API program has strong foundations in contract design, schema quality, and crawlability — partners and agents can find and read the spec reliably. The critical gaps are in agent understanding and runnable usability: AI agents lack the semantic operation context and a dedicated instructions file they need to act on the API autonomously, and there are no executable collections with test scripts to validate real workflows. Fixing agent understanding first, then adding runnable truth and enriching onboarding with embedded code samples, will meaningfully shorten the path from discovery to a working partner integration.