bookmark-create · Jj MCP: Risk & Policy

WHAT IT DOES

What bookmark-create does on Jj

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

WHY IT NEEDS A POLICY

Why bookmark-create needs a policy

This tool creates new bookmarks (named references) in version control history. While bookmarks are typically reversible via bookmark-delete, this is a write operation that modifies repository metadata.

From the tool's definition Tool description states it will 'Create a new bookmark' in a Jujutsu repository. The verb 'create' and the documented purpose of creating a named reference point indicate this is a write operation that modifies repository state.

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

bookmark-create Rate-limited

bookmark-create 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": {
    "bookmark-create": {
      "limits": [
        {
          "counter": "bookmark-create_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 Jj, so you can run agents against it safely.

FAQ

Questions about bookmark-create

What does the bookmark-create tool do? +

Create a new bookmark in a Jujutsu (jj) repository. Useful for marking important points in history or creating named branches. Parameters: name (Name of the bookmark to create), revision (Optional revision to point the bookmark at), repoPath (Optional path to repo root or working directory), cwd (Optional working directory to run the command in). It is categorised as a Write tool in the Jj MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on bookmark-create? +

Register the Jj MCP server in PolicyLayer and add a rule for bookmark-create: 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 Jj. Nothing to install.

What risk level is bookmark-create? +

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

Can I rate-limit bookmark-create? +

Yes. Add a rate_limit block to the bookmark-create 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 bookmark-create completely? +

Set action: deny in the PolicyLayer policy for bookmark-create. 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 bookmark-create? +

bookmark-create is provided by the Jj MCP server (jj-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.