# `europepmc__search_papers`

Search Europe PMC for papers (single source — prefer \`unified_search\` for
multi-source coverage).

- Server: [Europe PMC](https://gateway.mcpharbor.dev/docs/servers/europepmc) (`dev.mcpharbor.gateway/europepmc`)
- Price per call: $0.0001 (100 micro-USD); only tools/call is charged
- Endpoint: `https://gateway.mcpharbor.dev/mcp` or `https://gateway.mcpharbor.dev/mcp/europepmc`
- Upstream tool: exposed by the provider; called through this gateway as `europepmc__search_papers`
- Provider terms: <https://europepmc.org/Copyright> (verified 2026-09-19)
- Upstream API documentation: <https://europepmc.org/RestfulWebService>
- Rate limit: 500 requests per minute

## Parameters

- `limit` (integer, optional): Number of results Default: `25`.
- `query` (string, required): Search query
- `result_type` (string, optional): Europe PMC result type Default: `core`.
- `sort` (string, optional): Sort order, e.g. 'cited' or 'date' Default: ``.

## Example call

Request headers and body:

```http
POST /mcp HTTP/1.1
Host: gateway.mcpharbor.dev
Authorization: Bearer <your gateway API key>
Content-Type: application/json
Accept: application/json, text/event-stream
MCP-Protocol-Version: 2026-07-28
Mcp-Method: tools/call
Mcp-Name: europepmc__search_papers
```

```json
{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "_meta": {
      "io.modelcontextprotocol/clientCapabilities": {},
      "io.modelcontextprotocol/clientInfo": {
        "name": "example-agent",
        "version": "1.0.0"
      },
      "io.modelcontextprotocol/protocolVersion": "2026-07-28"
    },
    "arguments": {
      "query": "example"
    },
    "name": "europepmc__search_papers"
  }
}
```

A successful response:

```json
{
  "id": 1,
  "jsonrpc": "2.0",
  "result": {
    "_meta": {
      "dev.mcpharbor.gateway/call": {
        "chargedMicroUsd": 100,
        "id": "<the id of this charge>"
      }
    },
    "content": [
      {
        "text": "<whatever the upstream tool returned>",
        "type": "text"
      }
    ],
    "resultType": "complete"
  }
}
```

This call costs $0.0001 (100 micro-USD). Reading this page and listing the tool cost nothing.
The `dev.mcpharbor.gateway/call` record in the result is the receipt for that charge. Each
POST is metered separately, so sending the same call again buys another one: see
[agent.txt](https://gateway.mcpharbor.dev/agent.txt), section 7, before retrying.

## Attribution

This provider asks for no attribution. Their terms still apply: see the table above.

## Tool definition

Exactly as `tools/list` returns it (free):

```json
{
  "_meta": {
    "dev.mcpharbor.gateway/pricing": {
      "currency": "USD",
      "pricePerCallMicroUsd": 100
    }
  },
  "annotations": {
    "idempotentHint": true,
    "openWorldHint": true,
    "readOnlyHint": true,
    "title": "[Legacy] Search Europe PMC"
  },
  "description": "Search Europe PMC for papers (single source — prefer `unified_search` for\n    multi-source coverage).",
  "inputSchema": {
    "properties": {
      "limit": {
        "default": 25,
        "description": "Number of results",
        "maximum": 1000,
        "minimum": 1,
        "title": "Limit",
        "type": "integer"
      },
      "query": {
        "description": "Search query",
        "title": "Query",
        "type": "string"
      },
      "result_type": {
        "default": "core",
        "description": "Europe PMC result type",
        "title": "Result Type",
        "type": "string"
      },
      "sort": {
        "default": "",
        "description": "Sort order, e.g. 'cited' or 'date'",
        "title": "Sort",
        "type": "string"
      }
    },
    "required": [
      "query"
    ],
    "title": "search_papersArguments",
    "type": "object"
  },
  "name": "europepmc__search_papers",
  "outputSchema": {
    "properties": {
      "result": {
        "items": {
          "additionalProperties": true,
          "type": "object"
        },
        "title": "Result",
        "type": "array"
      }
    },
    "required": [
      "result"
    ],
    "title": "search_papersOutput",
    "type": "object"
  }
}
```