watch_global
Watches a global variable for changes. When the variable is modified, logs the old and new values to console.
This record as markdown: /tools/1600822305-js-reverse-mcp/watch-global.md
What watch_global does on Js Reverse
AI agents invoke watch_global to trigger actions in Js Reverse. 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 watch_global is rated High
The tool actively executes code within the browser context (via Chrome DevTools Protocol) to set up watchers/breakpoints on global variables. This constitutes executing code in an external runtime environment, not merely reading data. Misuse could allow monitoring sensitive global variables (e.g., auth tokens, credentials) in the browser context, making it medium severity.
From the tool's definition 'Watches a global variable for changes' — this injects monitoring logic (likely via CDP) into the browser runtime to intercept variable modifications and log old/new values to console.
Attacks that exploit this kind of access
The rule that runs watch_global safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Js Reverse, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For watch_global, this is the rule to start with:
watch_global 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 Js Reverse, apply this rule, and every watch_global call is checked against it from then on.
Questions about watch_global
Watches a global variable for changes. When the variable is modified, logs the old and new values to console. It is categorised as a Execute tool in the Js Reverse MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Js Reverse MCP server in PolicyLayer and add a rule for watch_global: 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 Js Reverse. Nothing to install.
watch_global 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 watch_global 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 watch_global. 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.
watch_global is provided by the Js Reverse MCP server (1600822305/js-reverse-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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