fill_form · BrowserPilot MCP: Risk & Policy

WHAT IT DOES

What fill_form does on BrowserPilot MCP

AI agents invoke fill_form to trigger actions in BrowserPilot MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why fill_form needs a policy

Filling form fields is a browser automation action that triggers external side effects depending on what form is being filled (login, purchase, submission, etc.). It spans Write and Execute; since it operates on external systems via browser automation with variable and potentially significant consequences, Execute is the most accurate category.

From the tool's definition 'Fill multiple form fields at once' in a browser automation context — executes browser actions that interact with external web forms

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

fill_form Rate-limited

fill_form stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "fill_form": {
      "limits": [
        {
          "counter": "fill_form_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches BrowserPilot MCP, so you can run agents against it safely.

FAQ

Questions about fill_form

What does the fill_form tool do? +

Fill multiple form fields at once. It is categorised as a Execute tool in the BrowserPilot MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on fill_form? +

Register the BrowserPilot 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 BrowserPilot MCP. Nothing to install.

What risk level is fill_form? +

fill_form is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit fill_form? +

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.

How do I block fill_form completely? +

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.

What MCP server provides fill_form? +

fill_form is provided by the BrowserPilot MCP server (sept-7-qi/browserpilot-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.