add_journal_entry · Hardcover MCP: Risk & Policy

WHAT IT DOES

What add_journal_entry does on Hardcover

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

WHY IT NEEDS A POLICY

Why add_journal_entry needs a policy

This tool creates a new journal entry (a note or quote), which is a reversible write operation. It does not delete, execute code, trigger external systems, or involve financial transactions. The blast radius of misuse is minimal—unwanted journal entries can be deleted via the sibling 'delete_journal_entry' tool.

From the tool's definition Tool name 'add_journal_entry' and description 'Create a reading journal entry' explicitly indicate creation of new data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_journal_entry Rate-limited

add_journal_entry 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": {
    "add_journal_entry": {
      "limits": [
        {
          "counter": "add_journal_entry_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 Hardcover, so you can run agents against it safely.

FAQ

Questions about add_journal_entry

What does the add_journal_entry tool do? +

Create a reading journal entry (for example a note or quote) for a book. It is categorised as a Write tool in the Hardcover MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_journal_entry? +

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

What risk level is add_journal_entry? +

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

Can I rate-limit add_journal_entry? +

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

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

add_journal_entry is provided by the Hardcover MCP server (kristianedlund/hardcover-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.