set_expire · Redis MCP: Risk & Policy

WHAT IT DOES

What set_expire does on Redis

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

WHY IT NEEDS A POLICY

Why set_expire needs a policy

set_expire modifies the TTL (time-to-live) of existing Redis keys, which is a reversible write operation that changes data state without permanently destroying it. This requires disabling the default read-only protection.

From the tool's definition Tool name 'set_expire' and description indicating it 'sets key expiration time' with requirement to 'disable read-only mode', demonstrating write capability that modifies key metadata.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_expire Rate-limited

set_expire 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": {
    "set_expire": {
      "limits": [
        {
          "counter": "set_expire_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 Redis, so you can run agents against it safely.

FAQ

Questions about set_expire

What does the set_expire tool do? +

设置键的过期时间（需要关闭只读模式）. It is categorised as a Write tool in the Redis MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_expire? +

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

What risk level is set_expire? +

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

Can I rate-limit set_expire? +

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

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

set_expire is provided by the Redis MCP server (lm203688/redis-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.