v8_heap_sampling

SERVERJshookmcp SOURCE@jshookmcp/jshook

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-vmoranv-jshookmcp/v8-heap-sampling.md

WHAT IT DOES

What v8_heap_sampling does on Jshookmcp

AI agents invoke v8_heap_sampling to trigger actions in Jshookmcp. 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.

RISK

Why v8_heap_sampling is rated High

Triggers live browser profiling via CDP, executing an external operation with runtime effects.

From the tool's definition Collect a V8 allocation sampling profile via CDP HeapProfiler

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs v8_heap_sampling safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Jshookmcp, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For v8_heap_sampling, this is the rule to start with:

v8_heap_sampling Rate-limited

v8_heap_sampling 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": {
    "v8_heap_sampling": {
      "limits": [
        {
          "counter": "v8_heap_sampling_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 Jshookmcp, apply this rule, and every v8_heap_sampling call is checked against it from then on.

FAQ

Questions about v8_heap_sampling

What does the v8_heap_sampling tool do? +

Collect a V8 allocation sampling profile via CDP HeapProfiler. Starts sampling for a capture window (default 5s), then returns the aggregated allocation call tree: per-function self/total bytes + sample count, sorted by total bytes allocated. Useful for finding hot allocation sites without a full heap snapshot. Requires browser/page CDP context. It is categorised as a Execute tool in the Jshookmcp MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on v8_heap_sampling? +

Register the Jshook MCP server in PolicyLayer and add a rule for v8_heap_sampling: 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 Jshookmcp. Nothing to install.

What risk level is v8_heap_sampling? +

v8_heap_sampling is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit v8_heap_sampling? +

Yes. Add a rate_limit block to the v8_heap_sampling 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 v8_heap_sampling completely? +

Set action: deny in the PolicyLayer policy for v8_heap_sampling. 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 v8_heap_sampling? +

v8_heap_sampling is provided by the Jshook MCP server (@jshookmcp/jshook). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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