describe_available_classes
AI agents call describe_available_classes to retrieve information from Alibaba Cloud RDS OpenAPI MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool appears to retrieve metadata about available database instance classes (SKU information) offered by Alibaba Cloud RDS. Such queries are informational only, with no ability to modify, delete, or execute operations. Even if misused by an agent, retrieving class availability data poses minimal risk. Classification as Read with low severity is appropriate.
From the tool's definition Tool name 'describe_available_classes' uses the describe verb, which conventionally retrieves or lists data without side effects. The empty description limits certainty, but the naming pattern aligns with querying available RDS instance classes/types.
Documented attack patterns abuse exactly the kind of access describe_available_classes gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Alibaba Cloud RDS OpenAPI MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for describe_available_classes:
{
"version": "1",
"default": "deny",
"tools": {
"describe_available_classes": {}
}
}describe_available_classes is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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describe_available_classes. It is categorised as a Read tool in the Alibaba Cloud RDS OpenAPI MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Alibaba Cloud RDS OpenAPI MCP Server MCP server in PolicyLayer and add a rule for describe_available_classes: 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 Alibaba Cloud RDS OpenAPI MCP Server. Nothing to install.
describe_available_classes 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 describe_available_classes 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 describe_available_classes. 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.
describe_available_classes is provided by the Alibaba Cloud RDS OpenAPI MCP Server MCP server (aliyun/alibabacloud-rds-openapi-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 37 Alibaba Cloud RDS OpenAPI MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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37 Alibaba Cloud RDS OpenAPI MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.