open_url

Open a URL in the default web browser

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/open-url.md

WHAT IT DOES

What open_url does on CoWork OS

AI agents invoke open_url 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 open_url is rated High

Opening a URL is not a pure read/query operation; it executes an action in the operating system (launching or directing a browser), and the URL could point to malicious pages, trigger downloads, or invoke custom protocol handlers. This makes it an Execute-category tool with medium severity due to the potential for misuse via crafted URLs.

From the tool's definition 'Open a URL in the default web browser' — triggers an external operation (launching the browser and navigating to a URL) whose effects depend on the URL argument

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs open_url 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 open_url, this is the rule to start with:

open_url Rate-limited

open_url 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": {
    "open_url": {
      "limits": [
        {
          "counter": "open_url_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 open_url call is checked against it from then on.

FAQ

Questions about open_url

What does the open_url tool do? +

Open a URL in the default web browser. 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 open_url? +

Register the CoWork OS MCP server in PolicyLayer and add a rule for open_url: 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 open_url? +

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

Can I rate-limit open_url? +

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

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

open_url 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

More on CoWork OS, and thousands of servers like it.

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All 342 CoWork OS tools → High-risk tools on this server →

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Guides

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