Get distinct values from a column (useful for understanding data distribution)
AI agents call sample_distinct to retrieve information from Database MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a SELECT DISTINCT operation, which is a read-only query. It retrieves data to show unique values in a column for analysis purposes, with no side effects, no modifications to data, and no destructive capability. Even in the context of a tool that can execute arbitrary queries on multiple database systems, this specific tool is explicitly scoped to safe introspection/exploration.
From the tool's definition Tool name 'sample_distinct' and description 'Get distinct values from a column' indicate a query operation that retrieves and displays data without modification.
Attacks that exploit this kind of access
Get distinct values from a column (useful for understanding data distribution). It is categorised as a Read tool in the Database MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Database MCP Server MCP server in PolicyLayer and add a rule for sample_distinct: 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 Database MCP Server. Nothing to install.
sample_distinct 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 sample_distinct 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 sample_distinct. 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.
sample_distinct is provided by the Database MCP Server MCP server (zeaozhang/database-mcp). 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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