file_reserve · Forgespec MCP: Risk & Policy

WHAT IT DOES

What file_reserve does on Forgespec

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

WHY IT NEEDS A POLICY

Why file_reserve needs a policy

The tool creates advisory locks/reservations on files, which is a reversible write operation (reservations expire after TTL). It modifies coordination state without reading, executing, or destroying data. Misuse could block other agents from accessing files, causing workflow disruption, hence medium severity.

From the tool's definition Reserve files or glob patterns to prevent conflicts between agents. Use check_only=true to check for conflicts without reserving. Reservations expire after TTL.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

file_reserve Rate-limited

file_reserve 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": {
    "file_reserve": {
      "limits": [
        {
          "counter": "file_reserve_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 Forgespec, so you can run agents against it safely.

FAQ

Questions about file_reserve

What does the file_reserve tool do? +

Reserve files or glob patterns to prevent conflicts between agents. Use check_only=true to check for conflicts without reserving. Reservations expire after TTL. It is categorised as a Write tool in the Forgespec MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on file_reserve? +

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

What risk level is file_reserve? +

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

Can I rate-limit file_reserve? +

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

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

file_reserve is provided by the Forgespec MCP server (lleontor705/forgespec-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.