AI agents call cache_flush_all 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.
Flushing all cache entries removes all cached data at once with no selective recovery. This is a bulk, irreversible destruction of cached state, qualifying as Destructive. The blast radius is high because it affects all cache entries simultaneously, potentially degrading performance or disrupting dependent services until the cache is repopulated.
From the tool's definition 'cache_flush_all' and 'Flush all cache entries' — flushing all cache entries is an irreversible bulk deletion of cached data
Risk signalsBulk/mass operation — affects multiple targets
Documented attack patterns abuse exactly the kind of access cache_flush_all 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 cache_flush_all:
{
"version": "1",
"default": "deny",
"hide": [
"cache_flush_all"
]
} cache_flush_all 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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Flush all cache entries. 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 cache_flush_all: 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.
cache_flush_all 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 cache_flush_all 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 cache_flush_all. 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.
cache_flush_all 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.