new

Server Jj jj-mcp-server

Category Write

Risk class Medium

Parameters 00 required

WHAT IT DOES

What new does on Jj

AI agents use new 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 new needs a policy

This tool creates a new change (similar to a commit) in the VCS repository. It is a write operation that modifies the repository state by adding a new change, but it is reversible (can be abandoned). No code execution, deletion, or financial impact.

From the tool's definition Create a new, empty change with optional parent revisions in a Jujutsu (jj) repository

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

new Rate-limited

new 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": {
    "new": {
      "limits": [
        {
          "counter": "new_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 new

What does the new tool do? +

Create a new, empty change with optional parent revisions in a Jujutsu (jj) repository. Useful for starting a new line of development or feature branch. Parameters: parents (Optional parent revisions, comma separated), repoPath (Optional repo path), 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 new? +

Register the Jj MCP server in PolicyLayer and add a rule for new: 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 new? +

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

Can I rate-limit new? +

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

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

new 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.