json_to_csv · Claude MCP Starter MCP: Risk & Policy

WHAT IT DOES

What json_to_csv does on Claude MCP Starter

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

WHY IT NEEDS A POLICY

Why json_to_csv needs a policy

This tool transforms JSON data and writes the result to a CSV file. It creates/writes a file on disk, which is a reversible Write operation. Misuse could overwrite existing files, but the blast radius is limited to file system changes.

From the tool's definition 'Convert a JSON array of objects to a CSV file' — creates a new CSV file as output

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

json_to_csv Rate-limited

json_to_csv 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": {
    "json_to_csv": {
      "limits": [
        {
          "counter": "json_to_csv_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 Claude MCP Starter, so you can run agents against it safely.

FAQ

Questions about json_to_csv

What does the json_to_csv tool do? +

Convert a JSON array of objects to a CSV file. It is categorised as a Write tool in the Claude MCP Starter MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on json_to_csv? +

Register the Claude MCP Starter MCP server in PolicyLayer and add a rule for json_to_csv: 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 Claude MCP Starter. Nothing to install.

What risk level is json_to_csv? +

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

Can I rate-limit json_to_csv? +

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

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

json_to_csv is provided by the Claude MCP Starter MCP server (justdreameritis/claude-mcp-starter). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.