List all available prefecture codes for weather forecast.
AI agents call list_prefectures to retrieve information from JMA Data MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a straightforward read-only operation that queries and returns metadata about available prefectures. It retrieves information without modifying, deleting, or executing any operations. The tool has minimal blast radius if misused by an AI agent, as it only returns informational data about supported geographic regions.
From the tool's definition Tool name 'list_prefectures' and description 'List all available prefecture codes for weather forecast' indicate a data retrieval operation with no side effects. Returns a static list of prefecture codes used for querying weather data.
Attacks that exploit this kind of access
List all available prefecture codes for weather forecast. It is categorised as a Read tool in the JMA Data MCP MCP Server, which means it retrieves data without modifying state.
Register the JMA Data MCP server in PolicyLayer and add a rule for list_prefectures: 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 JMA Data MCP. Nothing to install.
list_prefectures 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_prefectures 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_prefectures. 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_prefectures is provided by the JMA Data MCP server (koizumikento/jma-data-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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