cf_kv · Yaver MCP: Risk & Policy

WHAT IT DOES

What cf_kv does on Yaver

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

PARAMETERS

Parameter	Type	Required	Description
`key`	string	—
`value`	string	—
`action`	string	Yes	list, keys, get, put
`namespace`	string	—

Parameters from the server's own tool schema.

WHY IT NEEDS A POLICY

Why cf_kv needs a policy

An AI agent can call cf_kv faster than any human can review — one bad instruction and it creates or modifies resources in Yaver by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cf_kv Rate-limited

cf_kv 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": {
    "cf_kv": {
      "limits": [
        {
          "counter": "cf_kv_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 Yaver, so you can run agents against it safely.

FAQ

Questions about cf_kv

What does the cf_kv tool do? +

Manage Cloudflare KV store. It is categorised as a Write tool in the Yaver MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does cf_kv accept? +

cf_kv accepts 4 parameters: key, value, action, namespace. Required: action. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on cf_kv? +

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

What risk level is cf_kv? +

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

Can I rate-limit cf_kv? +

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

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

cf_kv is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.