mark_read · Lyceum MCP: Risk & Policy

WHAT IT DOES

What mark_read does on Lyceum

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

WHY IT NEEDS A POLICY

Why mark_read needs a policy

This tool creates or modifies data reversibly by updating a boolean read status and optional date fields in book metadata. It does not delete, destroy, execute arbitrary code, move money, or have irreversible consequences. The operation is easily reversible by calling the tool again with different parameters.

From the tool's definition 'Mark a book as read (or unread) in the library. Optionally provide a date; defaults to today. Pass read: false to clear the read date.' - This tool modifies metadata state (read status and date) for books in the library.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mark_read Rate-limited

mark_read 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": {
    "mark_read": {
      "limits": [
        {
          "counter": "mark_read_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 Lyceum, so you can run agents against it safely.

FAQ

Questions about mark_read

What does the mark_read tool do? +

Mark a book as read (or unread) in the library. Optionally provide a date; defaults to today. Pass read: false to clear the read date. It is categorised as a Write tool in the Lyceum MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on mark_read? +

Register the Lyceum MCP server in PolicyLayer and add a rule for mark_read: 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 Lyceum. Nothing to install.

What risk level is mark_read? +

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

Can I rate-limit mark_read? +

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

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

mark_read is provided by the Lyceum MCP server (matthewp/lyceum). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.