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Alibaba Cloud RDS OpenAPI MCP Server

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by aliyun

describe_available_classes

Read-only

Retrieve the purchasable RDS instance class codes and storage space ranges for a given region, zone, engine, and payment type.

Instructions

Query the RDS instance class_code and storage space that can be purchased in the inventory.

Args:
    region_id: The region ID of the RDS instance.
    zone_id: The zone ID of the RDS instance. Query available zones by `describe_available_zones`.
    instance_charge_type: Instance payment type. Values: Prepaid, Postpaid, Serverless.
    engine: Database engine type. Values: MySQL, SQLServer, PostgreSQL, MariaDB.
    engine_version: Database version.
    dbinstance_storage_type: Storage type. Values: local_ssd,general_essd,cloud_essd,cloud_essd2,cloud_essd3
    category: Instance category. Values: Basic, HighAvailability, cluster, AlwaysOn, Finance, serverless_basic, serverless_standard, serverless_ha.
    dbinstance_id: The ID of the RDS instance.
    order_type: Order type. Currently only supports "BUY".
    commodity_code: Commodity code for read-only instances.

Returns:
    Dict[str, Any]: The response containing available instance classes and storage ranges.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
region_idYes
zone_idYes
instance_charge_typeYes
engineYes
engine_versionYes
dbinstance_storage_typeYes
categoryYes
dbinstance_idNo
order_typeNo
commodity_codeNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description uses 'Query' which aligns with the readOnlyHint annotation. It discloses that it returns available instance classes and storage ranges, adding context about the inventory nature. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is front-loaded with the purpose and structured with Args/Returns sections. While it lists all parameters verbosely, each entry is informative. Slightly wordy but clear.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 10 parameters and no schema descriptions, the description covers all parameters meaningfully. It mentions a return type and hints (e.g., order_type only supports 'BUY'). Lacks error handling or pagination info, but sufficient for typical query tasks.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Since schema coverage is 0%, the description fully compensates by explaining each parameter's meaning and valid values (e.g., 'Values: Prepaid, Postpaid, Serverless' for instance_charge_type). This adds essential semantics beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it queries 'the RDS instance class_code and storage space that can be purchased in the inventory,' which is a specific verb and resource. It distinguishes itself from sibling tools like describe_available_zones by focusing on class and storage.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description cross-references describe_available_zones for querying zones, implying a workflow. It lists required parameters, providing context for when to use (e.g., when planning to purchase an instance). However, it does not explicitly state when not to use or list alternatives among siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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