AIError.invalidToolInput

Symptom

AIError.invalidToolInput(tool:reason:). The tool's own code never executed.

Why it happens

Arguments are validated against the tool's schema before the executor is called, so a malformed call fails closed rather than reaching your code with missing fields.

Smaller models get this wrong more often, especially with deeply nested schemas or unusual enum values.

Fix

Supply repairToolCall to fix a call and retry it instead of failing the run:

repairToolCall: { call, tools in
  guard call.name == "search" else { return nil }
  var fixed = call
  fixed.arguments = normalize(call.arguments)
  return fixed
}

Flattening the schema helps more than prompting does. So does adding inputExamples to the tool, which Anthropic sends natively and other providers can receive through the .addToolInputExamples() middleware.

See also

• Tools
• Errors