AI agents call list_crs_by_region to retrieve information from Epsg without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and lists coordinate reference system information filtered by geographic region. It is a pure read operation that returns reference data without side effects. No data is created, modified, deleted, or executed. The blast radius of misuse is minimal—an agent might retrieve irrelevant CRS suggestions, but this causes no harm to systems or data.
From the tool's definition Tool name 'list_crs_by_region' and description 'Get available CRS list for a region' indicate a query/retrieval operation.
Attacks that exploit this kind of access
Get available CRS list for a region with purpose-based recommendations. Japan includes Plane Rectangular CS (Zones I-XIX), Global includes WGS84 and UTM zones. It is categorised as a Read tool in the Epsg MCP Server, which means it retrieves data without modifying state.
Register the Epsg MCP server in PolicyLayer and add a rule for list_crs_by_region: 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 Epsg. Nothing to install.
list_crs_by_region 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 list_crs_by_region 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 list_crs_by_region. 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.
list_crs_by_region is provided by the Epsg MCP server (shuji-bonji/epsg-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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