AI agents call get_unique_values to retrieve information from QGIS MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation on GIS data—it queries and returns distinct field values from a layer. There is no data modification, deletion, code execution, or financial impact. The operation is purely informational retrieval, typical of Read category tools. The low severity reflects minimal blast radius even if an AI agent misuses it, as it cannot alter the GIS project state.
From the tool's definition Tool name 'get_unique_values' and description 'Return the distinct values of a field' indicate a query operation that retrieves data without modification or side effects.
Attacks that exploit this kind of access
Return the distinct values of a field. Use. It is categorised as a Read tool in the QGIS MCP MCP Server, which means it retrieves data without modifying state.
Register the QGIS MCP server in PolicyLayer and add a rule for get_unique_values: 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 QGIS MCP. Nothing to install.
get_unique_values 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 get_unique_values 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 get_unique_values. 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.
get_unique_values is provided by the QGIS MCP server (nkarasiak/qgis-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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