safari_evaluate_js

Runs arbitrary JavaScript in the current Safari tab and returns its result. Requires 'Allow JavaScript from Apple Events' in Safari's Develop menu.

SERVERLocal SOURCElocal-mcp

High RISK CLASS

Category Execute

Parameters 11 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/com-local-mcp-local-mcp/safari-evaluate-js.md

WHAT IT DOES

What safari_evaluate_js does on Local

AI agents invoke safari_evaluate_js to trigger actions in Local. 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.

Parameter	Type	Required	Description
`script`	string	Yes

Parameters from the server's own tool schema.

RISK

Why safari_evaluate_js is rated High

This tool executes arbitrary JavaScript code in a live browser tab. An AI agent could use it to exfiltrate data, manipulate DOM, perform actions on behalf of the user, or interact with any web application currently open. Arbitrary code execution in a browser context is critical severity due to the unlimited blast radius across all open web sessions.

From the tool's definition Runs arbitrary JavaScript in the current Safari tab

Risk signalsAccepts freeform code/query input (script)

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs safari_evaluate_js safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Local, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For safari_evaluate_js, this is the rule to start with:

safari_evaluate_js Rate-limited

safari_evaluate_js 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": {
    "safari_evaluate_js": {
      "limits": [
        {
          "counter": "safari_evaluate_js_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Local, apply this rule, and every safari_evaluate_js call is checked against it from then on.

FAQ

Questions about safari_evaluate_js

What does the safari_evaluate_js tool do? +

Runs arbitrary JavaScript in the current Safari tab and returns its result. Requires 'Allow JavaScript from Apple Events' in Safari's Develop menu. It is categorised as a Execute tool in the Local MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

What parameters does safari_evaluate_js accept? +

safari_evaluate_js accepts 1 parameter: script. Required: script. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on safari_evaluate_js? +

Register the Local MCP server in PolicyLayer and add a rule for safari_evaluate_js: 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 Local. Nothing to install.

What risk level is safari_evaluate_js? +

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

Can I rate-limit safari_evaluate_js? +

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

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

safari_evaluate_js is provided by the Local MCP server (local-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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