canvas_show

OPTIONAL: Open the canvas in a separate interactive window.

SERVERCoWork OS SOURCECoWork-OS/CoWork-OS

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/cowork-os/canvas-show.md

WHAT IT DOES

What canvas_show does on CoWork OS

AI agents invoke canvas_show to trigger actions in CoWork OS. 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 canvas_show is rated High

The tool triggers an external UI operation — opening a separate interactive window — which constitutes an action with side effects beyond simple data retrieval. It is not purely reading data, but rather executing a UI/display action. Severity is low since it only opens a window and has minimal blast radius if misused.

From the tool's definition Open the canvas in a separate interactive window

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs canvas_show safely

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

canvas_show Rate-limited

canvas_show 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": {
    "canvas_show": {
      "limits": [
        {
          "counter": "canvas_show_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 CoWork OS, apply this rule, and every canvas_show call is checked against it from then on.

FAQ

Questions about canvas_show

What does the canvas_show tool do? +

OPTIONAL: Open the canvas in a separate interactive window. It is categorised as a Execute tool in the CoWork OS MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on canvas_show? +

Register the CoWork OS MCP server in PolicyLayer and add a rule for canvas_show: 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 CoWork OS. Nothing to install.

What risk level is canvas_show? +

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

Can I rate-limit canvas_show? +

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

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

canvas_show is provided by the CoWork OS MCP server (CoWork-OS/CoWork-OS). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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