> ## Documentation Index
> Fetch the complete documentation index at: https://docs.bridger.kr/llms.txt
> Use this file to discover all available pages before exploring further.

# POST /mcp (JSON-RPC)

> The MCP-standard JSON-RPC 2.0 endpoint — tools/list, tools/call.

The core MCP call endpoint of the Bridger Gateway. It follows the JSON-RPC 2.0 spec exactly.

## Request headers

```http theme={null}
POST /mcp HTTP/1.1
Content-Type: application/json
x-api-key: dk_live_...
```

## Common error codes

| Code     | Meaning                                 |
| -------- | --------------------------------------- |
| `-32600` | Invalid JSON-RPC request                |
| `-32601` | Method not found                        |
| `-32602` | Invalid params (e.g. missing tool name) |
| `-32000` | Internal gateway error                  |

## tools/list

Returns metadata for every tool registered with Bridger.

### Request

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}
```

### Response 200

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "tools": [
      {
        "name": "pingtool",
        "description": "Ping endpoint",
        "inputSchema": { "type": "object", "properties": {} },
        "annotations": {
          "readOnlyHint": true,
          "destructiveHint": false,
          "openWorldHint": false
        }
      }
    ]
  }
}
```

## tools/call

Runs a single tool.

### Request

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "pingtool",
    "arguments": { "q": "hello" }
  }
}
```

### Response 200

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "tool": "pingtool",
    "upstream": {
      "method": "GET",
      "url": "http://127.0.0.1:9921/ping?q=hello",
      "status": 200
    },
    "data": { "ok": true, "q": "hello" },
    "cacheStatus": "MISS",
    "auditId": "aud_..."
  }
}
```

| Field                    | Description                                                        |
| ------------------------ | ------------------------------------------------------------------ |
| `result.tool`            | Called tool name                                                   |
| `result.upstream.method` | Upstream HTTP method                                               |
| `result.upstream.url`    | Final upstream URL (after middleware injection such as ServiceKey) |
| `result.upstream.status` | Upstream HTTP status code                                          |
| `result.data`            | Upstream response body (after XML→JSON normalization)              |
| `result.cacheStatus`     | Whether the cache was hit (`HIT`/`MISS`, etc.)                     |
| `result.auditId`         | Audit-log identifier for this call                                 |

## Full cURL examples

<CodeGroup>
  ```bash tools/list theme={null}
  curl -X POST https://mcp.datari.kr/mcp \
    -H "x-api-key: $DATA_BRIDGE_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'
  ```

  ```bash tools/call theme={null}
  curl -X POST https://mcp.datari.kr/mcp \
    -H "x-api-key: $DATA_BRIDGE_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "jsonrpc": "2.0",
      "id": 2,
      "method": "tools/call",
      "params": {
        "name": "pingtool",
        "arguments": { "q": "hello" }
      }
    }'
  ```
</CodeGroup>

## Automatic public-data middleware behavior

When calling a tool from a preset with `isPublicData=true`, the following are applied automatically.

1. ServiceKey injection (`PUBLIC_DATA_SERVICE_KEY`)
2. `lat/lon` → `nx/ny` grid coordinate conversion (KMA DFS)
3. XML/JSON payload normalization
4. Public-data error code → human-readable message mapping

| Code  | Message                              |
| ----- | ------------------------------------ |
| `00`  | OK                                   |
| `30`  | Unregistered service key             |
| `31`  | Expired service key                  |
| `32`  | Unregistered IP                      |
| other | `Unknown public-data error (<code>)` |