Brexbrex.com
Brex's API program shows strong API design fundamentals and solid agent discoverability foundations, but two areas are holding back partner outcomes: agent understanding and developer experience. AI agents and coding assistants lack the structured context files, machine-readable doc formats, and explicit instruction guides they need to build integrations autonomously — increasing the risk of hallucinated or broken implementations.
API DesignA clean, typed, well-governed API contract agents can reason about2 pass3 warn0 fail81A
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Auth declared & discoverablevia docs | 25/25 | Authentication required (global or on every operation). Investigated: docs 100%, wellknown 100%, spec 55%. | Agents can only authenticate when auth is declared, scoped, and discoverable. |
| warn | Machine-readable, versioned contractvia spec | 18.8/25 | info.version="1.0" 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. |
| warn | Schema coverage & depthvia spec | 18.3/25 | Only 69% of operations have documented schemas. Investigated: spec 73%, sdk 0%. | Typed, complete request/response schemas are what make agent function-calling possible. |
| pass | Security & governance hygienevia spec | 15/15 | No credential-shaped strings detected in spec. Investigated: spec 100%, wellknown 50%. | No leaked secrets, no critical lint violations, no OWASP API Top-10 spec smells, and a published vulnerability-disclosure channel. |
| warn | Example coveragevia spec | 0.5/10 | 0% example coverage. Investigated: spec 5%, docs 0%, sdk 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 warn2 fail66C
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Self-service developer portalvia docs | 29/29 | Signup page at https://www.brex.com/signup; no free-tier language detected in docs/pricing. Investigated: docs 100%. | Self-serve key/account creation is the fast first call for partners, with no sales gate. |
| pass | Description completenessvia spec | 15/15 | 43% description completeness. Investigated: spec 100%. | Complete descriptions are the context humans and agents need to use endpoints. |
| pass | Changelog publishedvia spec | 13/13 | changelog documented in the docs site at https://developer.brex.com/changelog. Investigated: spec 100%, docs 100%. | A published changelog lets partners track changes without surprise. |
| fail | Quickstart presentvia docs | 0/25 | No quickstart/getting-started page found at the conventional paths. Investigated: docs 0%. | A quickstart is the fastest path from landing page to first successful call. |
| fail | Code samples in docsvia docs | 0/18 | No detectable code samples across 20 sampled docs pages. Investigated: docs 0%. | Multi-language samples shorten time-to-first-call. |
Agent DiscoveryPartners and their agents can find your APIs — llms.txt, registries, crawlable and reachable docs1 pass3 warn0 fail76B
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Registry & SDK presencevia docs | 28/28 | Indexed on Context7 (websites/developer_brex_guides, 112 snippets). Investigated: docs 100%, sdk 100%, cli 0%, mcp 0%, wellknown 0%. | Listing in MCP registries and publishing SDKs puts the API where agents and their tooling look. |
| warn | llms.txt present, valid & comprehensivevia docs | 22.5/30 | No llms.txt directive found in HTML of any of 50 sampled pages. Investigated: docs 75%. | A valid, comprehensive llms.txt is the machine-readable entry point for agents. |
| warn | Docs reachable, not hard auth-gatedvia docs | 15/30 | 38 of 50 sampled pages return 200 for non-existent URLs (soft 404). Investigated: docs 50%. | Agents can only index and fetch docs they can reach — past auth gates and over correct HTTP semantics. |
| warn | Crawlable / AEOvia wellknown | 6/12 | robots.txt blocks 2 of 7 monitored AI crawlers on docs paths (google-extended, ccbot). Investigated: wellknown 50%. | 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 docs1 pass3 warn2 fail75B
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Machine-readable errors (RFC 9457)via docs | 28/28 | No 4xx/5xx response codes (or default error response) documented anywhere in the spec. Investigated: docs 100%, spec 50%. | RFC 9457 problem details and a documented error-code inventory let agents parse failures without burning tokens. |
| warn | Operation purpose clarityvia spec | 22.5/25 | 86% of operations are agent-inferable (target 90%+). Investigated: spec 90%. | 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 | 17.6/22 | 2 of 48 pages have substantive content differences between markdown and HTML (avg 2% missing). Investigated: docs 80%. | Server-rendered, clean, small-footprint docs are what an agent can cheaply fetch and parse correctly. |
| warn | Description consistency across surfaces | 1.2/7 | Mean pairwise description similarity across 2 surfaces (spec, docs) is 6% (threshold 35% for full credit). | Every surface tells the same story about what the product is. |
| 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. |
| fail | Docs structured datavia docs | 0/8 | Neither JSON-LD nor OpenGraph/meta tags detected across 2 assessed pages (2 JS-rendered). Investigated: docs 0%. | 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. |
Agent UsabilityAgents have the context to use your APIs reliably, not just find them2 pass1 warn2 fail63C
| Signal | Points | Findings | Rationale | |
|---|---|---|---|---|
| pass | Pagination documented & consistentvia spec | 22/22 | Cursor pagination detected (most robust for agents). Investigated: spec 100%, docs 100%. | Consistent, documented pagination lets agents traverse collections. |
| pass | Sandbox separationvia spec | 20/20 | Sandbox server declared but no distinguishable test credentials in scheme descriptions. Investigated: spec 100%, docs 100%. | An isolated environment lets agents exercise destructive operations safely. |
| warn | Idempotency documentedvia spec | 10.1/27 | 0% of mutating operations document idempotency. Investigated: spec 38%, docs 38%. | 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 | 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. |
Resources Discovered
The public resources we found for Brex — the evidence behind the score. All discovered from public sources; nothing here requires access to your systems.
| Agent hints | Context7 (112) |
|---|---|
| APIs analyzed | 10 — Team API, Budgets API, Webhooks API, Fields API, Payments API, Transactions API, Expenses API, Accounting API, Onboarding API, Travel API |