Fill a complete form with one call — the preferred way to submit any form with 2+ fields. Each field needs ref or CSS selector plus value. Supports text inputs, <select> (by value or visible label), checkboxes (boolean), and radio buttons. Use this INSTEAD of multiple type calls or evaluate-setti...
Part of the Chrome server.
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AI agents use fill_form to create or modify resources in Chrome. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call fill_form repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Chrome.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"fill_form": {
"limits": [
{
"counter": "fill_form_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Chrome policy for all 23 tools.
These attack patterns abuse exactly the kind of access fill_form gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Fill a complete form with one call — the preferred way to submit any form with 2+ fields. Each field needs ref or CSS selector plus value. Supports text inputs, <select> (by value or visible label), checkboxes (boolean), and radio buttons. Use this INSTEAD of multiple type calls or evaluate-setting select.value: one round-trip, partial errors do not abort, each field reports its own status. On per-field errors, call view_page and retry the failing fields — DO NOT escape to evaluate(querySelector) to patch individual fields; it bypasses framework state management (React, Vue) and hides real bugs.. It is categorised as a Write tool in the Chrome MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Chrome MCP server in PolicyLayer and add a rule for fill_form: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Chrome. Nothing to install.
fill_form is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the fill_form rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for fill_form. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
fill_form is provided by the Chrome MCP server (@silbercue/chrome). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 23 Chrome tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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