tag_snapshot · Restic MCP: Risk & Policy

WHAT IT DOES

What tag_snapshot does on Restic

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

WHY IT NEEDS A POLICY

Why tag_snapshot needs a policy

Tagging a snapshot modifies metadata on existing backup snapshots (adding or removing tags). This is a reversible write operation — tags can be re-added or removed again. It does not delete data, execute code, or move money.

From the tool's definition Add or remove tags on a backup snapshot

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

tag_snapshot Rate-limited

tag_snapshot 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": {
    "tag_snapshot": {
      "limits": [
        {
          "counter": "tag_snapshot_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 Restic, so you can run agents against it safely.

FAQ

Questions about tag_snapshot

What does the tag_snapshot tool do? +

Add or remove tags on a backup snapshot. It is categorised as a Write tool in the Restic MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on tag_snapshot? +

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

What risk level is tag_snapshot? +

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

Can I rate-limit tag_snapshot? +

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

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

tag_snapshot is provided by the Restic MCP server (mohsenil85/restic-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.