convert_to_fits · Astro MCP: Risk & Policy

WHAT IT DOES

What convert_to_fits does on Astro MCP

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

WHY IT NEEDS A POLICY

Why convert_to_fits needs a policy

The tool converts data from one format to another, which constitutes a modification of data. However, this is a reversible operation (data can be converted back), with no irreversible deletion, no code execution with unpredictable effects, and no financial impact. It operates on already-saved files within the astronomical data context, making it a Write-category tool.

From the tool's definition Tool description states 'Convert saved data files to FITS format using astropy', which is a data transformation/conversion operation that modifies the format of existing data files.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

convert_to_fits Rate-limited

convert_to_fits 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": {
    "convert_to_fits": {
      "limits": [
        {
          "counter": "convert_to_fits_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 Astro MCP, so you can run agents against it safely.

FAQ

Questions about convert_to_fits

What does the convert_to_fits tool do? +

Convert saved data files to FITS format using astropy. It is categorised as a Write tool in the Astro MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on convert_to_fits? +

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

What risk level is convert_to_fits? +

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

Can I rate-limit convert_to_fits? +

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

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

convert_to_fits is provided by the Astro MCP server (sandyyuan/astro_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.