prettier-format
Formats files with Prettier (--write) and returns a structured list of changed files.
This record as markdown: /tools/io-github-dave-london-pare-test/prettier-format.md
What prettier-format does on Test
AI agents use prettier-format to create or update resources in Test, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Test environment.
Why prettier-format is rated Medium
This tool modifies file contents by applying code formatting, which is a reversible write operation. While the changes can theoretically be undone (e.g., through version control), the tool itself irreversibly overwrites the original file contents with formatted versions during execution. This qualifies as Write rather than Destructive because formatting is reversible via standard development workflows.
From the tool's definition The tool description states it "Formats files with Prettier (--write)" which modifies files on disk. The --write flag explicitly indicates file content is being altered and written back.
Attacks that exploit this kind of access
The rule that runs prettier-format safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Test, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For prettier-format, this is the rule to start with:
prettier-format 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 Test, apply this rule, and every prettier-format call is checked against it from then on.
Questions about prettier-format
Formats files with Prettier (--write) and returns a structured list of changed files. It is categorised as a Write tool in the Test MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Test MCP server in PolicyLayer and add a rule for prettier-format: 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 Test. Nothing to install.
prettier-format 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 prettier-format 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 prettier-format. 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.
prettier-format is provided by the Test 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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