install_skill_from_url · Friday MCP Server MCP

WHAT IT DOES

What install_skill_from_url does on Friday MCP Server

AI agents invoke install_skill_from_url to trigger actions in Friday MCP Server. 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 IT NEEDS A POLICY

Why install_skill_from_url needs a policy

This tool downloads code from an external URL and installs it as an executable skill, optionally activating it immediately. This is essentially remote code execution — an attacker could supply a malicious URL pointing to harmful skill code. The blast radius is critical because it can introduce arbitrary new capabilities into the MCP server environment.

From the tool's definition 'Download, validate, install, and optionally activate a skill from a URL' — fetches and installs executable skill code from an arbitrary remote URL, with optional immediate activation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

install_skill_from_url Rate-limited

install_skill_from_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": {
    "install_skill_from_url": {
      "limits": [
        {
          "counter": "install_skill_from_url_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Friday MCP Server, so you can run agents against it safely.

FAQ

Questions about install_skill_from_url

What does the install_skill_from_url tool do? +

Download, validate, install, and optionally activate a skill from a URL. It is categorised as a Execute tool in the Friday MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on install_skill_from_url? +

Register the Friday MCP Server MCP server in PolicyLayer and add a rule for install_skill_from_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 Friday MCP Server. Nothing to install.

What risk level is install_skill_from_url? +

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

Can I rate-limit install_skill_from_url? +

Yes. Add a rate_limit block to the install_skill_from_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 install_skill_from_url completely? +

Set action: deny in the PolicyLayer policy for install_skill_from_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 install_skill_from_url? +

install_skill_from_url is provided by the Friday MCP Server MCP server (jeremylakeyjr/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.