AI bot - Custom tools

Documentation Site Management
, ,
10

I’m seeing a tool schema error when adding a custom tool with an array parameter. Error on conversation start:

{
“error”: {
“code”: 400,
“message”: “* GenerateContentRequest.tools[0].function_declarations[3].parameters.properties[properties].items: missing field.\n”,
“status”: “INVALID_ARGUMENT”
}
}

What I tried:

  • Created a custom tool with a parameter named properties of type array.
  • The parameter list UI doesn’t allow specifying items.
  • Exported/imported a full tool JSON that includes items: { type: “string” } for properties.
  • After importing, the error persists as soon as the tool is enabled for a persona. If I remove the tool, the bot works.

Expected:

Either the parameter list UI should allow defining array item types, or the import should honor items so the schema validates.

Has anyone seen this? Is there a known limitation or a required UI path for defining array params?

1 Like