v8_deopt_trace
Trace V8 deoptimization events during a capture window. Primary path uses CDP Tracing (v8 category, V8.DeoptimizeFrame events — no natives syntax needed, structured reason/type/line data, timestamps aligned with profiler_cpu). Falls back to %TraceDeoptimizations console parsing when Tracing is un...
This record as markdown: /tools/io-github-vmoranv-jshookmcp/v8-deopt-trace.md
What v8_deopt_trace does on Jshookmcp
AI agents invoke v8_deopt_trace 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.
Why v8_deopt_trace is rated High
Triggers runtime tracing via CDP or V8 natives, executing external browser/engine operations.
From the tool's definition Trace V8 deoptimization events during a capture window
Attacks that exploit this kind of access
The rule that runs v8_deopt_trace 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_deopt_trace, this is the rule to start with:
v8_deopt_trace 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Jshookmcp, apply this rule, and every v8_deopt_trace call is checked against it from then on.
Questions about v8_deopt_trace
Trace V8 deoptimization events during a capture window. Primary path uses CDP Tracing (v8 category, V8.DeoptimizeFrame events — no natives syntax needed, structured reason/type/line data, timestamps aligned with profiler_cpu). Falls back to %TraceDeoptimizations console parsing when Tracing is unavailable (requires V8 natives syntax). 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.
Register the Jshook MCP server in PolicyLayer and add a rule for v8_deopt_trace: 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.
v8_deopt_trace 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 v8_deopt_trace 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 v8_deopt_trace. 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.
v8_deopt_trace 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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