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Fix: AI Assistant Not Filling Custom Fields With Custom Tools
When a custom tool doesn't fill a custom field, check each part in order: the tool's description clearly tells the AI when to call it, the parameter names are lowercase with underscores and their descriptions state the exact data and format wanted, the endpoint URL is correct, and authorization is set if the endpoint requires it.
A custom field that stays empty after a call usually traces back to one part of the custom tool setup, not a platform issue. Walk through how to create a custom tool to extract data and fill custom fields again with this checklist.
What to check
- Description. This is what tells the AI when to call the tool at all. A vague description means the AI may never trigger it during the conversation, so nothing reaches the field. Make it explicit: what the tool does and the exact moment to call it.
- Parameter names and format. Parameter names must be lowercase JSON-style — underscores, no spaces or special characters. If a parameter name doesn’t match what your endpoint expects, the data the AI extracts never lands where you need it.
- Parameter descriptions. Each parameter’s description should state precisely what to extract and in what format (for example, “the annualized revenue in raw number format”). A vague description produces inconsistent or wrongly formatted output from the AI.
- Endpoint URL. Confirm it’s the correct POST endpoint, and that it’s reachable.
- Authorization. If the endpoint requires an API key or auth header, confirm the Bearer Token field is filled in correctly — an authorization failure on the endpoint side can look identical to the tool simply not firing.
Test it directly
Have a test conversation that clearly matches the tool’s description, then check the conversation logs for a “task performed” entry showing the tool was called and what data it sent — this tells you whether the AI called the tool at all, versus the tool firing but the endpoint rejecting the data.
Still stuck?
Contact Assistantz.ai support on WhatsApp with the tool’s configuration and a transcript of a failed attempt.