AI agents call list_cache_keys to retrieve information from OpenAPI Directory 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 query/enumeration of cache metadata. It retrieves information about what is cached but does not modify cache contents, execute operations, delete data, or have financial implications. The blast radius of misuse is minimal—an agent could learn what APIs or specs are cached but cannot affect their integrity or trigger unwanted actions.
From the tool's definition The tool name 'list_cache_keys' and description 'List all cache keys' indicate a read-only operation that retrieves information about cached items without modifying, deleting, or executing anything.
Documented attack patterns abuse exactly the kind of access list_cache_keys gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and OpenAPI Directory MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list_cache_keys:
{
"version": "1",
"default": "deny",
"tools": {
"list_cache_keys": {}
}
}list_cache_keys is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all cache keys. It is categorised as a Read tool in the OpenAPI Directory MCP Server MCP Server, which means it retrieves data without modifying state.
Register the OpenAPI Directory MCP Server MCP server in PolicyLayer and add a rule for list_cache_keys: 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 OpenAPI Directory MCP Server. Nothing to install.
list_cache_keys 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_cache_keys 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_cache_keys. 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_cache_keys is provided by the OpenAPI Directory MCP Server MCP server (rawveg/openapi-directory-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from OpenAPI Directory MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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22 OpenAPI Directory MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.