AI agents call fetch_spec_page to retrieve information from J Quants Doc without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool fetches specification/documentation pages, which is a read-only operation with no side effects. The empty description reduces confidence slightly, but the name and server purpose clearly indicate data retrieval rather than modification, execution, or destructive actions. Low severity given it only retrieves information about API specifications.
From the tool's definition Tool name 'fetch_spec_page' and server context indicate data retrieval. Server description emphasizes 'searching J-Quants API endpoints, retrieving detailed documentation'—fetch_spec_page aligns with documentation retrieval.
Documented attack patterns abuse exactly the kind of access fetch_spec_page gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and J Quants Doc, and nothing reaches the server without passing your rules. This is the rule we recommend for fetch_spec_page:
{
"version": "1",
"default": "deny",
"tools": {
"fetch_spec_page": {}
}
}fetch_spec_page is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
fetch_spec_page. It is categorised as a Read tool in the J Quants Doc MCP Server, which means it retrieves data without modifying state.
Register the J Quants Doc MCP server in PolicyLayer and add a rule for fetch_spec_page: 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 J Quants Doc. Nothing to install.
fetch_spec_page 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 fetch_spec_page 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 fetch_spec_page. 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.
fetch_spec_page is provided by the J Quants Doc MCP server (j-quants/j-quants-doc-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from J Quants Doc, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
7 J Quants Doc tools catalogued and risk-classified — across an index of 43,000+ MCP servers.