json_clear

THE RISK

Critical Risk

Why json_clear needs a policy

Clearing a container (array or object) at a given path irreversibly removes all its contents. This is a destructive operation that cannot be undone, similar to purging or dropping data. The blast radius is high because a misconfigured path could wipe out significant portions of a data structure in Prometheus/AWS Managed Prometheus configuration or state.

From the tool's definition Clear container at path (array or object)

Documented attack patterns abuse exactly the kind of access json_clear gives an agent:

POLICY

How to control json_clear

PolicyLayer is an MCP gateway — it sits between your AI agents and Prometheus MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for json_clear:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "json_clear"
  ]
}

json_clear disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

Create a free account and register Prometheus MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Prometheus MCP Server tools

Destructive bulk_delete_by_criteria bulk_delete_by_criteria Destructive cache_delete Delete a value from the cache. Destructive cache_delete_many Delete multiple values from the cache. Destructive cache_delete_multi Delete multiple values from the cache (alias for delete_many). Destructive delete delete Destructive delete_access_key delete_access_key Destructive delete_agent_runtime delete_agent_runtime Destructive delete_agent_runtime_endpoint delete_agent_runtime_endpoint

All 805 Prometheus MCP Server tools →

Destructive tools on other servers

Android Forensics ADB MCP Server create_full_backup 0xarchive web3_revoke_key Frida Game Hacking MCP clear_scan cPanel MCP Server clear_spam_box

Go deeper

Critical-risk tools in Prometheus MCP Server → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about json_clear

What does the json_clear tool do? +

Clear container at path (array or object). It is categorised as a Destructive tool in the Prometheus MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on json_clear? +

Register the Prometheus MCP Server MCP server in PolicyLayer and add a rule for json_clear: 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 Prometheus MCP Server. Nothing to install.

What risk level is json_clear? +

json_clear is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit json_clear? +

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

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

json_clear is provided by the Prometheus MCP Server MCP server (awslabs.prometheus-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Prometheus MCP Server tool call.

Start from Prometheus MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →