Form validation errors an AI agent can recover from

A useful validation error identifies the field, explains the problem, and preserves the user’s other work. A generic “Something went wrong” does not tell an agent how to repair the input.

Check the visitor’s path

• Attach errors to the relevant fields and summarize multiple issues clearly.
• Explain the expected format with a concrete example when needed.
• Keep valid values after a failed submission.
• Distinguish incorrect input from a temporary server problem.

If a postcode field rejects spaces, say what format is accepted rather than silently clearing the form. Better still, accept reasonable formatting variations when the underlying address remains the same.