page_coverage_start
Start JS+CSS code coverage collection on the active page. Coverage tracks which bytes of each loaded script/stylesheet are actually executed. Use page_coverage_stop to stop collection and retrieve results.
This record as markdown: /tools/io-github-vmoranv-jshookmcp/page-coverage-start.md
What page_coverage_start does on Jshookmcp
AI agents invoke page_coverage_start 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 page_coverage_start is rated High
Initiates browser automation action that instruments and monitors code execution, affecting page behavior.
From the tool's definition Start JS+CSS code coverage collection on the active page
Attacks that exploit this kind of access
The rule that runs page_coverage_start 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 page_coverage_start, this is the rule to start with:
page_coverage_start 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 page_coverage_start call is checked against it from then on.
Questions about page_coverage_start
Start JS+CSS code coverage collection on the active page. Coverage tracks which bytes of each loaded script/stylesheet are actually executed. Use page_coverage_stop to stop collection and retrieve results. 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 page_coverage_start: 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.
page_coverage_start 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 page_coverage_start 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 page_coverage_start. 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.
page_coverage_start 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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