Execute JavaScript in page context. Supports single expressions and multi-statement code. Returns the completion value of the last expression-statement.
Part of the Charlotte server.
Free to start. No card required.
AI agents invoke charlotte_evaluate to trigger processes or run actions in Charlotte. Execute operations can have side effects beyond the immediate call -- triggering builds, sending notifications, or starting workflows. Rate limits and argument validation are essential to prevent runaway execution.
charlotte_evaluate can trigger processes with real-world consequences. An uncontrolled agent might start dozens of builds, send mass notifications, or kick off expensive compute jobs. PolicyLayer enforces rate limits and validates arguments to keep execution within safe bounds.
Execute tools trigger processes. Rate-limit and validate arguments to prevent unintended side effects.
{
"version": "1",
"default": "deny",
"tools": {
"charlotte_evaluate": {
"limits": [
{
"counter": "charlotte_evaluate_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}See the full Charlotte policy for all 43 tools.
These attack patterns abuse exactly the kind of access charlotte_evaluate gives an agent. Each links to the full case and the policy that stops it:
Other execute tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Execute JavaScript in page context. Supports single expressions and multi-statement code. Returns the completion value of the last expression-statement.. It is categorised as a Execute tool in the Charlotte MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Charlotte MCP server in PolicyLayer and add a rule for charlotte_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 Charlotte. Nothing to install.
charlotte_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 charlotte_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 charlotte_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.
charlotte_evaluate is provided by the Charlotte MCP server (@ticktockbent/charlotte). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 43 Charlotte tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.