Postmarkapppostmarkapp.com
Postmarkapp's API program shows real strengths in documentation reachability and schema clarity, but partners and their agents face three compounding blockers today: the API cannot be safely or reliably automated (missing sandbox, idempotency guidance, and rate-limit signaling), runnable examples are absent so agents must guess at request shapes, and there is no machine-readable instruction layer to help AI agents understand how to work with the API. Fixing agent usability and runnable truth first will have the most immediate impact on partner integration success, followed by closing the auth discoverability and example coverage gaps that slow both human and agent onboarding.
API DesignA clean, typed, well-governed API contract agents can reason about1 pass2 warn2 fail60C
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| warn | Machine-readable, versioned contractvia spec | 18.8/25 | info.version="1.0.0" set but no versioning scheme (URL / header / media type) detected. Investigated: spec 75%, docs 50%. | A current OpenAPI version with a declared versioning scheme lets agents reason about the contract. |
| pass | Security & governance hygienevia spec | 15/15 | No credential-shaped strings detected in spec. Investigated: spec 100%, wellknown 0%. | No leaked secrets, no critical lint violations, no OWASP API Top-10 spec smells, and a published vulnerability-disclosure channel. |
| warn | Schema coverage & depthvia spec | 14.6/25 | Only 70% of operations have documented schemas. Investigated: spec 58%. | Typed, complete request/response schemas are what make agent function-calling possible. |
| fail | Auth declared & discoverablevia spec | 0/25 | No securitySchemes declared. Investigated: spec 0%, docs 0%. | Agents can only authenticate when auth is declared, scoped, and discoverable. |
| fail | Example coveragevia spec | 0/10 | 0% example coverage. Investigated: spec 0%. | Examples carry shape semantics schemas under-specify — for humans and agents alike. |
Developer ExperienceThe context both developers and agents need to integrate fast — onboarding, code samples, complete descriptions and worked examples3 pass0 warn1 fail71B
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Quickstart presentvia docs | 25/25 | Quickstart at https://postmarkapp.com/developer/get-started with a runnable first-call sample. Investigated: docs 100%. | A quickstart is the fastest path from landing page to first successful call. |
| pass | Description completenessvia spec | 15/15 | 71% description completeness (target 90%+). Investigated: spec 100%. | Complete descriptions are the context humans and agents need to use endpoints. |
| pass | Changelog publishedvia sdk | 13/13 | Newest official SDK activity 3 day(s) ago. Investigated: sdk 100%, spec 0%, docs 0%. | A published changelog lets partners track changes without surprise. |
| fail | Self-service developer portalvia docs | 0/29 | No signup page detected across conventional paths (/signup, /sign-up, /register, /get-started, /console/signup, /dashboard/signup, /try, /try-free, /free, /free-trial, /start, /start-free). Investigated: docs 0%. | Self-serve key/account creation is the fast first call for partners, with no sales gate. |
| na | Code samples in docs | —/18 | No surface produced evidence for this capability in this run. | Multi-language samples shorten time-to-first-call. |
Agent DiscoveryPartners and their agents can find your APIs — llms.txt, registries, crawlable and reachable docs2 pass2 warn0 fail79B
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Registry & SDK presencevia docs | 28/28 | Indexed on Context7 (websites/postmarkapp_developer, 1085 snippets). Investigated: docs 100%, sdk 100%, cli 0%. | Listing in MCP registries and publishing SDKs puts the API where agents and their tooling look. |
| warn | Docs reachable, not hard auth-gatedvia docs | 22.5/30 | Server ignores Accept: text/markdown header (0/50 sampled pages return markdown); 40 rate-limited (HTTP 429). Investigated: docs 75%. | Agents can only index and fetch docs they can reach — past auth gates and over correct HTTP semantics. |
| warn | llms.txt present, valid & comprehensivevia docs | 13.1/30 | llms.txt covers 17/51 sitemap doc pages (33%); 34 missing. Investigated: docs 44%. | A valid, comprehensive llms.txt is the machine-readable entry point for agents. |
| pass | Crawlable / AEOvia wellknown | 12/12 | Docs paths crawlable by all monitored AI agents. Investigated: wellknown 100%. | Bots allowed plus a fresh sitemap make docs findable by agent crawlers. |
Agent UnderstandingAgents can correctly interpret your APIs — machine-readable errors, consistent descriptions, structured data, parseable docs2 pass1 warn1 fail79B
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Machine-readable errors (RFC 9457)via spec | 28/28 | Only 2 distinct 4xx/5xx codes documented (plus 0 "default" catch-all responses). Investigated: spec 100%, docs 100%. | RFC 9457 problem details and a documented error-code inventory let agents parse failures without burning tokens. |
| pass | Operation purpose clarityvia spec | 25/25 | 95% of operations have a clear summary + operationId an agent can select on. Investigated: spec 100%. | Agents select the right endpoint from its summary + operationId; clear, named operations make tool-selection reliable — the strongest driver of correct tool choice. |
| warn | Agent-navigable, token-efficient docsvia docs | 11/22 | No sampled pages support .md URLs (0/50 tested). Investigated: docs 50%. | Server-rendered, clean, small-footprint docs are what an agent can cheaply fetch and parse correctly. |
| fail | Agent instructions file (AGENTS.md)via wellknown | 0/10 | No AGENTS.md at the site root or /.well-known/. Investigated: wellknown 0%. | An AGENTS.md gives coding agents explicit setup, auth, and usage instructions to interpret and operate the API — beyond llms.txt's link index. |
| na | Docs structured data | —/8 | No surface produced evidence for this capability in this run. | Structured data (JSON-LD/schema.org) on docs pages gives agents an unambiguous parse target and is what answer engines cite. Detected on the JS-rendered head (Firecrawl) for a bounded page budget, so JS-injected JSON-LD is now caught; pages we can't render are excluded rather than failed. |
| na | Description consistency across surfaces | —/7 | Only 1 surface description(s) with ≥6 tokens available; need at least 2 to compare. | Every surface tells the same story about what the product is. |
Agent UsabilityAgents have the context to use your APIs reliably, not just find them0 pass0 warn4 fail40F
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| fail | Idempotency documentedvia spec | 0/27 | 0% of mutating operations document idempotency. Investigated: spec 0%, docs 0%. | Documented idempotency lets agents retry safely. |
| fail | Rate-limit signalingvia spec | 0/22 | No rate-limit response headers documented. Investigated: spec 0%, docs 0%. | Machine-readable rate-limit headers let agents throttle adaptively. |
| fail | Sandbox separationvia spec | 0/20 | No sandbox/test server declared across 1 server entries; no test-key prefixes documented. Investigated: spec 0%, docs 0%. | An isolated environment lets agents exercise destructive operations safely. |
| fail | Runnable collection with test scriptsvia platform | 0/9 | No public Postman workspace discovered for the org. Investigated: platform 0%. | A public, maintained collection with assertions is runnable truth agents validate against. |
| na | Pagination documented & consistent | —/22 | No surface produced evidence for this capability in this run. | Consistent, documented pagination lets agents traverse collections. |
Resources Discovered
The public resources we found for Postmarkapp — the evidence behind the score. All discovered from public sources; nothing here requires access to your systems.
| Agent hints | Context7 (1,085) |
|---|---|
| APIs analyzed | 2 — Postmark API, Postmark Account-level API |