# invalid_call

URL: /evidence/errors/invalid_call · Id: `error:invalid_call`

> An MCP tool call named an unknown operation or sent input it cannot read.

The `invalid_call` [Problem](/evidence/errors) means: an MCP tool call named an unknown operation or sent input it cannot read.

## Answer
| Status | Title |
| --- | --- |
| 400 | Bad Request |

```json
{
  "type": "about:blank",
  "title": "Bad Request",
  "status": 400,
  "detail": "What went wrong, in words.",
  "code": "invalid_call"
}
```

## Fix
Call `search` for the operation, then `do` with its verb and input.