flake-update
Updates flake lock file inputs and returns structured information about what was updated.
This record as markdown: /tools/io-github-dave-london-npm/flake-update.md
What flake-update does on Npm
AI agents use flake-update to create or update resources in Npm, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Npm environment.
Why flake-update is rated Medium
This tool modifies a lock file (flake.lock), which is a reversible write operation. While lock files affect dependency resolution, the changes are not destructive (can be reverted) and don't execute arbitrary code or delete data. Lock file updates are Write operations with medium severity due to potential for introducing breaking changes to project dependencies if misused by an AI agent.
From the tool's definition Tool name 'flake-update' and description 'Updates flake lock file inputs' indicates modification of configuration files. The verb 'Updates' and explicit mention of writing to 'flake lock file' shows data modification.
Attacks that exploit this kind of access
The rule that runs flake-update safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Npm, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For flake-update, this is the rule to start with:
flake-update 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Npm, apply this rule, and every flake-update call is checked against it from then on.
Questions about flake-update
Updates flake lock file inputs and returns structured information about what was updated. It is categorised as a Write tool in the Npm MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Npm MCP server in PolicyLayer and add a rule for flake-update: 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 Npm. Nothing to install.
flake-update is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the flake-update 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.
Set action: deny in the PolicyLayer policy for flake-update. 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.
flake-update is provided by the Npm MCP server (Dave-London/Pare). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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