Get the number of keys stored in the Valkey database.
AI agents call dbsize to retrieve information from Prometheus MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs a query operation to retrieve metadata about database size/key count. This is a typical read operation with no side effects, no data modification, no code execution, and no destructive capability. The blast radius of misuse is minimal—returning a count of keys poses no security or operational risk.
From the tool's definition Tool name 'dbsize' and description 'Get the number of keys stored in the Valkey database' indicate a read-only query operation that retrieves database statistics without modifying or executing operations.
Documented attack patterns abuse exactly the kind of access dbsize 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 dbsize:
{
"version": "1",
"default": "deny",
"tools": {
"dbsize": {}
}
}dbsize is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get the number of keys stored in the Valkey database. It is categorised as a Read tool in the Prometheus MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Prometheus MCP Server MCP server in PolicyLayer and add a rule for dbsize: 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.
dbsize is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the dbsize 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 dbsize. 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.
dbsize 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.
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805 Prometheus MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.