AI agents call db_size to retrieve information from Redis without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves statistical information about the Redis database (key count) with no side effects. It is a read-only operation consistent with the server's design to support 'safely view' operations. The blast radius of misuse is minimal—an attacker could only learn database size, which is low-sensitivity metadata.
From the tool's definition Tool name 'db_size' and description 'get the number of keys in the current database' indicate a query operation that retrieves database metadata without modifying or deleting data.
Attacks that exploit this kind of access
获取当前数据库的键数量. It is categorised as a Read tool in the Redis MCP Server, which means it retrieves data without modifying state.
Register the Redis MCP server in PolicyLayer and add a rule for db_size: 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 Redis. Nothing to install.
db_size 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 db_size 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 db_size. 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.
db_size is provided by the Redis MCP server (lm203688/redis-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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