# `pubchem__pubchem_get_compound_image`

**Get Compound Image**

Fetch a 2D structure diagram (PNG image) for a compound by CID.

- Server: [PubChem](https://gateway.mcpharbor.dev/docs/servers/pubchem) (`dev.mcpharbor.gateway/pubchem`)
- 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/pubchem`
- Upstream tool: exposed by the provider; called through this gateway as `pubchem__pubchem_get_compound_image`
- Provider terms: <https://www.ncbi.nlm.nih.gov/home/about/policies/> (verified 2026-09-19)
- Upstream API documentation: <https://pubchem.ncbi.nlm.nih.gov/docs/pug-rest>
- Rate limit: 350 requests per minute
- Attribution required: Attribution to source recommended, not mandatory

## Parameters

- `cid` (integer, required): PubChem Compound ID. Resolve from name/SMILES with pubchem_search_compounds.
- `size` (string, optional): Image size: "small" (100x100) or "large" (300x300). Default: "large". One of: `small`, `large`. Default: `large`.

## 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: pubchem__pubchem_get_compound_image
```

```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": {
      "cid": 1
    },
    "name": "pubchem__pubchem_get_compound_image"
  }
}
```

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 requires the attribution below wherever you use results from its tools.
Reproduce it verbatim:

> Attribution to source recommended, not mandatory

## 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
  },
  "description": "Fetch a 2D structure diagram (PNG image) for a compound by CID.",
  "inputSchema": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "additionalProperties": false,
    "properties": {
      "cid": {
        "description": "PubChem Compound ID. Resolve from name/SMILES with pubchem_search_compounds.",
        "exclusiveMinimum": 0,
        "maximum": 9007199254740991,
        "type": "integer"
      },
      "size": {
        "default": "large",
        "description": "Image size: \"small\" (100x100) or \"large\" (300x300). Default: \"large\".",
        "enum": [
          "small",
          "large"
        ],
        "type": "string"
      }
    },
    "required": [
      "cid"
    ],
    "type": "object"
  },
  "name": "pubchem__pubchem_get_compound_image",
  "outputSchema": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "additionalProperties": false,
    "anyOf": [
      {
        "not": {
          "required": [
            "error"
          ]
        },
        "required": [
          "cid",
          "imageBase64",
          "mimeType",
          "width",
          "height"
        ]
      },
      {
        "required": [
          "error"
        ]
      }
    ],
    "properties": {
      "cid": {
        "description": "PubChem Compound ID.",
        "type": "number"
      },
      "error": {
        "additionalProperties": {},
        "description": "Present when the call failed. Absent on success.",
        "properties": {
          "code": {
            "description": "JSON-RPC error code for this failure.",
            "maximum": 9007199254740991,
            "minimum": -9007199254740991,
            "type": "integer"
          },
          "data": {
            "additionalProperties": {},
            "properties": {
              "reason": {
                "description": "Machine-readable failure mode. Declared by this tool: `cid_not_found`: PubChem returned 404 for the requested CID. Other values are possible when a failure originates below the handler.",
                "examples": [
                  "cid_not_found"
                ],
                "type": "string"
              },
              "recovery": {
                "additionalProperties": {},
                "description": "Actionable next step for the caller.",
                "properties": {
                  "hint": {
                    "type": "string"
                  }
                },
                "required": [
                  "hint"
                ],
                "type": "object"
              },
              "retryable": {
                "description": "Whether retrying may succeed.",
                "type": "boolean"
              }
            },
            "type": "object"
          },
          "message": {
            "description": "Human-readable description of what went wrong.",
            "type": "string"
          }
        },
        "required": [
          "code",
          "message"
        ],
        "type": "object"
      },
      "height": {
        "description": "Image height in pixels.",
        "type": "number"
      },
      "imageBase64": {
        "description": "Base64-encoded PNG image data.",
        "type": "string"
      },
      "mimeType": {
        "description": "MIME type — always \"image/png\".",
        "type": "string"
      },
      "width": {
        "description": "Image width in pixels.",
        "type": "number"
      }
    },
    "type": "object"
  },
  "title": "Get Compound Image"
}
```