# SiteCheck Health & Travel – MeSH Biomedical Thesaurus Lookup

> SiteCheck Health & Travel – MeSH Biomedical Thesaurus Lookup is a paid API for AI agents from api.healthtravel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-29).

Looks up a MeSH (Medical Subject Headings) descriptor by its exact heading, returning the descriptor ID, entry terms, and allowable qualifiers from the NLM linked data service.

## Facts

- Endpoint: GET https://api.healthtravel-api.workers.dev/api/health/mesh-biomedical-thesaurus?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-health-travel-mesh-biomedical-thesaurus-lookup-a5286724
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MoCmF97Q94zt7IW3kp76q

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sitecheck-health-travel-mesh-biomedical-thesaurus-lookup-a5286724
```

Example prompt: Look up the MeSH biomedical thesaurus entry for 'Aspirin' — I need its descriptor ID, all entry term synonyms, and what qualifiers are allowed.

## When to prefer this

Choose this endpoint when you need authoritative MeSH metadata (descriptor IDs, synonyms, allowable qualifiers) from the NLM linked data source, especially for indexing, ontology enrichment, or clinical NLP pipelines. It is preferable to ad-hoc web searches when you need structured, machine-readable MeSH data with no API key or signup required, and when pay-per-call economics are acceptable.

## Known failure modes

- Heading not found in MeSH — returns an error or empty result if the term is not a recognized MeSH descriptor
- Heading exceeds character constraints (must be 2–100 chars) or contains invalid characters — schema validation error
- NLM upstream service unavailable — upstream timeout or error propagated
- Misspelled or non-canonical heading — may return no match even if a similar term exists
- Payment failure — call is not charged if it fails, but agent must retry with valid payment

## How this service works

NLM MeSH (Medical Subject Headings) descriptor for an exact heading: MeSH ID, label, entry terms (synonyms) and allowable subheadings (qualifiers). Exact match only; no scope notes (the public lookup API does not return them).

## Output

Returns a JSON object containing: the source URL (NLM MeSH linked data), the queried heading, a timestamp, a list of entry terms each labeled as preferred or non-preferred, the MeSH descriptor ID (e.g. D001241), and an array of allowable qualifiers (e.g. 'adverse effects', 'administration & dosage').

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "heading"
     ],
     "properties": {
      "heading": {
       "type": "string",
       "description": "Exact MeSH heading, letters, digits, spaces, commas, hyphens and parentheses, 2 to 100 characters"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "source": "https://id.nlm.nih.gov/mesh/",
  "heading": "Aspirin",
  "checkedAt": "2026-10-23T09:36:25.547Z",
  "entryTerms": [
   {
    "label": "Aspirin",
    "preferred": true
   },
   {
    "label": "2-(Acetyloxy)benzoic Acid",
    "preferred": false
   }
  ],
  "descriptorId": "D001241",
  "allowableQualifiers": [
   "administration & dosage",
   "adverse effects"
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-health-travel-mesh-biomedical-thesaurus-lookup-a5286724/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.healthtravel-api.workers.dev](https://www.zero.xyz/host/api.healthtravel-api.workers.dev/llms.txt)