lerna

Runs Lerna monorepo commands (list, run, changed, version) and returns structured package information.

SERVERBuild SOURCEDave-London/Pare

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-dave-london-build/lerna.md

WHAT IT DOES

What lerna does on Build

AI agents invoke lerna to trigger actions in Build. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.

RISK

Why lerna is rated High

The 'run' subcommand in Lerna executes arbitrary package scripts, which can trigger build processes, test suites, and other code execution whose effects depend on what scripts are configured in the monorepo. This qualifies as Execute rather than Write because it triggers external operations (script execution) that can have unpredictable side effects.

From the tool's definition Tool 'runs Lerna monorepo commands' including 'run' which executes arbitrary scripts across multiple packages in a monorepo. While 'list' and 'changed' are read-only, the 'run' command allows execution of lifecycle scripts defined in package.json files.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs lerna safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Build, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For lerna, this is the rule to start with:

lerna Rate-limited

lerna stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "lerna": {
      "limits": [
        {
          "counter": "lerna_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Build, apply this rule, and every lerna call is checked against it from then on.

FAQ

Questions about lerna

What does the lerna tool do? +

Runs Lerna monorepo commands (list, run, changed, version) and returns structured package information. It is categorised as a Execute tool in the Build MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on lerna? +

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

What risk level is lerna? +

lerna is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit lerna? +

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

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

lerna is provided by the Build MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Build, and thousands of servers like it.

This server

All 202 Build tools → High-risk tools on this server →

Across the catalogue

All high-risk MCP tools → The MCP Attack Database →

Guides

Govern code and CI agents →Agent sandbox →Least privilege for MCP →