canvas_memory_invariants
Assert runtime invariants about WebGL context lifetime, engine state consistency, and texture/program leaks. Reports checks[], violations[] (with severity + safe-cleanup fix), and a recommendations[] block. Honest scope: only JS-observable metrics (DOM canvas count vs live WebGL contexts, rendere...
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What canvas_memory_invariants does on Jshookmcp
AI agents call canvas_memory_invariants to retrieve information from Jshookmcp without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why canvas_memory_invariants is rated Low
Tool audits WebGL state and memory without modifying or executing code; purely diagnostic.
From the tool's definition Assert runtime invariants, reports checks, violations, recommendations. JS-observable metrics only.
Attacks that exploit this kind of access
The rule that runs canvas_memory_invariants 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 canvas_memory_invariants, this is the rule to start with:
canvas_memory_invariants is read-only, so it stays allowed. 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 canvas_memory_invariants call is checked against it from then on.
Questions about canvas_memory_invariants
Assert runtime invariants about WebGL context lifetime, engine state consistency, and texture/program leaks. Reports checks[], violations[] (with severity + safe-cleanup fix), and a recommendations[] block. Honest scope: only JS-observable metrics (DOM canvas count vs live WebGL contexts, renderer.info.memory counts, contextLoss events). Full GC sweep / native-heap inspection is out of scope. Academic basis: JSidentify-V2 arXiv 2508.01655. It is categorised as a Read tool in the Jshookmcp MCP Server, which means it retrieves data without modifying state.
Register the Jshook MCP server in PolicyLayer and add a rule for canvas_memory_invariants: 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.
canvas_memory_invariants is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the canvas_memory_invariants 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 canvas_memory_invariants. 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.
canvas_memory_invariants 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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