playwright_fill_by_index

WHAT IT DOES

What playwright_fill_by_index does on Playwright MCP Server for Security

AI agents invoke playwright_fill_by_index to trigger actions in Playwright MCP Server for Security. 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 playwright_fill_by_index needs a policy

Filling an input field triggers real-world interactions on web pages — it can submit credentials, enter commands, populate forms that trigger backend operations, or feed data into security-sensitive fields. The server is explicitly labeled for security use, increasing the blast radius.

From the tool's definition Fill an input field by its annotation index number

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

playwright_fill_by_index Rate-limited

playwright_fill_by_index 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": {
    "playwright_fill_by_index": {
      "limits": [
        {
          "counter": "playwright_fill_by_index_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 Playwright MCP Server for Security, so you can run agents against it safely.

FAQ

Questions about playwright_fill_by_index

What does the playwright_fill_by_index tool do? +

Fill an input field by its annotation index number. Use playwright_annotate or playwright_get_annotated_elements first to get element indices. It is categorised as a Execute tool in the Playwright MCP Server for Security MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on playwright_fill_by_index? +

Register the Playwright MCP Server for Security MCP server in PolicyLayer and add a rule for playwright_fill_by_index: 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 Playwright MCP Server for Security. Nothing to install.

What risk level is playwright_fill_by_index? +

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

Can I rate-limit playwright_fill_by_index? +

Yes. Add a rate_limit block to the playwright_fill_by_index 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 playwright_fill_by_index completely? +

Set action: deny in the PolicyLayer policy for playwright_fill_by_index. 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 playwright_fill_by_index? +

playwright_fill_by_index is provided by the Playwright MCP Server for Security MCP server (o0x1024/mcp-playwright-security). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.