Evaluate JavaScript expression in the main Electron process
AI agents invoke electron_evaluate to trigger actions in Playwright MCP with Electron Support. 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.
This tool executes arbitrary JavaScript in the Electron main process, which has full Node.js access including filesystem, network, and OS-level APIs. An AI agent could use this to run any code on the host system, making it a critical Execute risk with an extremely large blast radius.
From the tool's definition Evaluate JavaScript expression in the main Electron process
Documented attack patterns abuse exactly the kind of access electron_evaluate gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Playwright MCP with Electron Support, and nothing reaches the server without passing your rules. This is the rule we recommend for electron_evaluate:
{
"version": "1",
"default": "deny",
"tools": {
"electron_evaluate": {
"limits": [
{
"counter": "electron_evaluate_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}electron_evaluate 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.
Free to start. No card required.
Evaluate JavaScript expression in the main Electron process. It is categorised as a Execute tool in the Playwright MCP with Electron Support MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Playwright MCP with Electron Support MCP server in PolicyLayer and add a rule for electron_evaluate: 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 with Electron Support. Nothing to install.
electron_evaluate is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the electron_evaluate 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.
Set action: deny in the PolicyLayer policy for electron_evaluate. 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.
electron_evaluate is provided by the Playwright MCP with Electron Support MCP server (robertn702/playwright-mcp-electron). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Playwright MCP with Electron Support, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
34 Playwright MCP with Electron Support tools catalogued and risk-classified — across an index of 43,000+ MCP servers.