Guards
Guards are what Willow checks in every tool call. They're account settings: they apply to every assistant in your account, and they aren't part of the safety score.
To change them, open an assistant's page, click the Safety pill in the header, and scroll to Willow's guards. Use the switch beside a guard to turn it on or off.
The guards
| Guard | What it does | To start |
|---|---|---|
| Prompt injection | Blocks content that tries to give the assistant new instructions, like a page or an email telling it to ignore yours. | On, for what tools send back |
| Secrets and API keys | Masks API keys, access tokens, passwords and private keys. | Off |
| Email addresses | Masks email addresses. | Off, and skips email apps when on |
| Phone numbers | Masks US and international phone numbers. | Off |
| Card and bank details | Masks card numbers, security codes and expiry dates, IBANs, and bank account and routing numbers. | Off |
| ID numbers | Masks Social Security numbers, passport and driver's license numbers, and tax IDs. | Off |
| Home addresses and birth dates | Masks street addresses, postcodes, coordinates and dates of birth. Off at first, since they're often what a task is about. | Off, for what tools send back |
Masked data is replaced before the AI sees it, so the assistant can still do the task without reading the value.
Configure a guard
Click Configure on a guard:
- Check: Both ways, What it sends to tools, or What tools send back. A guard that checks one side only shows an arrow beside its name.
- On: Every MCP server, Only these MCP servers, or Every MCP server except these. For the last two, pick the servers. Your assistants' servers are listed first.
Click Save. Reset to default puts the guard back the way it started.
When a guard breaks an app
Some apps need the data a guard masks. When you turn on a guard that would break one of your apps, Willow warns you, for example "Gmail needs email addresses to work. Masking them breaks its tools." Click Skip Gmail (or Skip them for several) to keep the guard on everywhere else, or Turn off if those apps were all it covered.
| Guard | Apps it breaks |
|---|---|
| Email addresses | Gmail, Google Calendar, Google Workspace, Outlook, Outlook Calendar, SendGrid, lemlist and Apollo |
| Phone numbers | Twilio and Bird |
The Email addresses guard skips the email apps from the start.