domain_filter · Perplexity MCP Server MCP: Risk & Policy

WHAT IT DOES

What domain_filter does on Perplexity MCP Server

AI agents use domain_filter to create or update resources in Perplexity MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Perplexity MCP Server environment.

WHY IT NEEDS A POLICY

Why domain_filter needs a policy

This tool creates or modifies search filter settings. While it writes/persists configuration state, it causes no destructive side effects—the changes are reversible through clear_filters or reconfiguration. It does not execute external code, delete data, or move money.

From the tool's definition Configures domain filtering for search results. The tool modifies filter settings/state, which is a reversible configuration change.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

domain_filter Rate-limited

domain_filter 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "domain_filter": {
      "limits": [
        {
          "counter": "domain_filter_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about domain_filter

What does the domain_filter tool do? +

Configure domain filtering for search results. Use. It is categorised as a Write tool in the Perplexity 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 domain_filter? +

Register the Perplexity MCP Server MCP server in PolicyLayer and add a rule for domain_filter: 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 Perplexity MCP Server. Nothing to install.

What risk level is domain_filter? +

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

Can I rate-limit domain_filter? +

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

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

domain_filter is provided by the Perplexity MCP Server MCP server (rossh121/perplexity-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.