save_url · MCP Wayback Machine Server MCP: Risk & Policy

WHAT IT DOES

What save_url does on MCP Wayback Machine Server

AI agents use save_url to create or update resources in MCP Wayback Machine Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Wayback Machine Server environment.

WHY IT NEEDS A POLICY

Why save_url needs a policy

This tool creates new snapshots in the Internet Archive by saving URLs, which is a reversible data modification operation. It does not execute arbitrary code, delete data, or move money. While saving to a public archive is a permanent action in the archive's timeline, the operation itself is Write-category as individual snapshots can theoretically be removed or marked.

From the tool's definition Tool description states 'Save a URL to the Wayback Machine', indicating creation of new archived records. The name 'save_url' and verb 'Save' are indicative of write operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

save_url Rate-limited

save_url stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "save_url": {
      "limits": [
        {
          "counter": "save_url_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about save_url

What does the save_url tool do? +

Save a URL to the Wayback Machine. It is categorised as a Write tool in the MCP Wayback Machine Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on save_url? +

Register the MCP Wayback Machine Server MCP server in PolicyLayer and add a rule for save_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 MCP Wayback Machine Server. Nothing to install.

What risk level is save_url? +

save_url is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit save_url? +

Yes. Add a rate_limit block to the save_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 save_url completely? +

Set action: deny in the PolicyLayer policy for save_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 save_url? +

save_url is provided by the MCP Wayback Machine Server MCP server (pl974/mcp-wayback-machine). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.