Errors

The Vault MCP Server returns errors as either JSON-RPC errors for transport and protocol problems, or tool execution errors for failures inside an executing agent action.

JSON-RPC Errors

JSON-RPC errors use the standard JSON-RPC 2.0 error object. The HTTP status code on the response indicates the specific condition.

Code	Description
`-32700`	Parse error. Invalid JSON received by the server.
`-32600`	Invalid request. The JSON sent is not a valid JSON-RPC request object.
`-32601`	Method not found. The requested method is not supported. For example, `prompts/list` and `resources/list` are not supported by this server.
`-32602`	Invalid params. Invalid parameter name or missing required argument.
`-32000`	Server error. Returned for transport errors, authentication failures, invalid session IDs, and rate-limit responses. The HTTP status code on the response indicates which condition applied.

Tool Execution Errors

Tool execution errors occur when an agent action fails for a business logic reason, such as an invalid argument value or insufficient permission on a document. The server returns HTTP 200 OK and includes isError: true in the response payload. The error message appears in the content array.

{
  "result": {
    "isError": true,
    "content": [{
      "type": "text",
      "text": "Error: Document 1001_1_3 not found, or you do not have permission to access it."
    }]
  }
}