# PubMed Bibliographic Search via NCBI eSearch

> PubMed Bibliographic Search via NCBI eSearch is a paid API for AI agents from project-api-gamma-sable.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).

Searches the NCBI PubMed database for biomedical literature and returns a slim JSON list of matching article IDs plus a UI link, paid per call via USDC on Base.

## Facts

- Endpoint: GET https://project-api-gamma-sable.vercel.app/paid/pubmed/search?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pubmed-bibliographic-search-via-ncbi-esearch-549c5f6d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__X6yVU-5CqNo8-bnkvbf0

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 pubmed-bibliographic-search-via-ncbi-esearch-549c5f6d
```

Example prompt: Search PubMed for the latest articles on CRISPR gene therapy and return up to 10 results.

## When to prefer this

Choose this endpoint when you need programmatic, pay-per-call access to PubMed bibliographic search results without managing an NCBI API key, and when your agent infrastructure already supports x402 micropayments in USDC on Base. It is well-suited for AI agents that need to dynamically retrieve scientific literature references on demand at low cost ($0.01/call).

## Known failure modes

- HTTP 402 returned if payment is not included or USDC on Base is not provided
- Empty items array if no articles match the search term
- Missing required 'term' query parameter causes a 400 or error response
- Rate limiting or upstream NCBI outage may cause timeouts or 5xx errors
- Invalid or malformed query strings may return zero results without explicit error

## How this service works

Paid public-data feeds. Unpaid requests return HTTP 402. Prices are USDC on Base.

## Output

Returns a slim JSON object containing a list of matching PubMed article items (typically IDs and minimal bibliographic info), a source path indicator, a description of the query type (NCBI eSearch), and a UI link to view results directly on PubMed.

## 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": [
      "term"
     ],
     "properties": {
      "q": {
       "type": "string",
       "description": "Free-text query"
      },
      "term": {
       "type": "string",
       "description": "Search term"
      },
      "limit": {
       "type": "string",
       "description": "Max results"
      },
      "offset": {
       "type": "string",
       "description": "Result offset"
      },
      "retmax": {
       "type": "string",
       "description": "Query param: retmax"
      },
      "retstart": {
       "type": "string",
       "description": "Query param: retstart"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "what": "NCBI PubMed bibliographic search via esearch (slim JSON + uiLink)",
  "items": [],
  "source": "/paid/pubmed/search"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pubmed-bibliographic-search-via-ncbi-esearch-549c5f6d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from project-api-gamma-sable.vercel.app](https://www.zero.xyz/host/project-api-gamma-sable.vercel.app/llms.txt)