fill-search

THE RISK

Medium Risk

Why fill-search needs a policy

This tool creates/modifies data in a browser input field reversibly. It does not execute code, delete data, or cause financial impact. While it interacts with a search interface, the modification of an input field is fundamentally a write operation. The severity is low because misuse would only result in executing unintended searches, which are easily corrected.

From the tool's definition Tool description states 'Fill the search input field with a query', which modifies form input state. The action is reversible (can be cleared or overwritten) and has no destructive consequences.

Documented attack patterns abuse exactly the kind of access fill-search gives an agent:

POLICY

How to control fill-search

PolicyLayer is an MCP gateway — it sits between your AI agents and MoltBrowser MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for fill-search:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "fill-search": {
      "limits": [
        {
          "counter": "fill-search_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

fill-search stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register MoltBrowser MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More MoltBrowser MCP Server tools

Destructive contribute_delete-tool Delete a specific tool from a WebMCP Hub config. The config owner or the tool\ Execute hub_execute Execute a pre-configured hub tool for the current site. After navigating, the response wil Execute click-compose-button Click the compose/new tweet button to open the tweet editor Execute click-post-button Click the Post button to submit the tweet Write contribute_vote-on-tool Upvote or downvote a tool within a WebMCP Hub config. Each user gets one vote per tool — v Write fill-tweet-text Fill the tweet text area with content Read get-article Get the main article text Read get-posts Get all visible posts on the page

All 9 MoltBrowser MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about fill-search

What does the fill-search tool do? +

Fill the search input field with a query. After calling this, use browser_press_key({ key: \. It is categorised as a Write tool in the MoltBrowser MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on fill-search? +

Register the MoltBrowser MCP Server MCP server in PolicyLayer and add a rule for fill-search: 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 MoltBrowser MCP Server. Nothing to install.

What risk level is fill-search? +

fill-search is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit fill-search? +

Yes. Add a rate_limit block to the fill-search 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-search completely? +

Set action: deny in the PolicyLayer policy for fill-search. 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-search? +

fill-search is provided by the MoltBrowser MCP Server MCP server (joakim-sael/moltbrowser). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MoltBrowser MCP Server tool call.

Start from MoltBrowser MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →