Pop a value from the array at path and index.
AI agents call json_arrpop to permanently remove resources in Prometheus MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Popping a value from an array removes it permanently from the data store. Unlike an update that overwrites with a new value, a pop operation deletes the element at a specific index without the ability to undo it, classifying it as Destructive. The blast radius is high given this operates on a Prometheus/AWS managed data store where data loss could affect monitoring and alerting infrastructure.
From the tool's definition 'Pop a value from the array at path and index' — removing/popping an element from an array is a destructive, irreversible mutation of stored data
Documented attack patterns abuse exactly the kind of access json_arrpop gives an agent:
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_arrpop:
{
"version": "1",
"default": "deny",
"hide": [
"json_arrpop"
]
}json_arrpop disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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Pop a value from the array at path and index. 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.
Register the Prometheus MCP Server MCP server in PolicyLayer and add a rule for json_arrpop: 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.
json_arrpop is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the json_arrpop 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.
Set action: deny in the PolicyLayer policy for json_arrpop. 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.
json_arrpop 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.
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.
Free to start. No card required.
805 Prometheus MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.