DescribeRegions

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states what the tool does (query) without mentioning whether it's a read-only operation, if it requires authentication, rate limits, or what the output format looks like. For a query tool with no annotation coverage, this leaves critical behavioral traits unspecified.

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

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

The description is a single, efficient sentence that directly states the tool's function without unnecessary words. It's front-loaded with the core purpose and mentions key parameters, making it easy to understand at a glance. Every part of the sentence contributes to clarifying the tool's intent.

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

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

Given the tool's complexity (4 parameters, no output schema, no annotations), the description is minimally adequate. It covers the basic purpose but lacks details on output format, error handling, or when to use it relative to siblings. For a query tool with no output schema, the description should ideally hint at the return structure, but it doesn't, leaving gaps in completeness.

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

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

The schema description coverage is 100%, with detailed descriptions for all four parameters including enums and defaults. The description adds minimal value beyond the schema by mentioning '计费方式、资源类型等参数' (billing method, resource type, and other parameters), which aligns with the schema but doesn't provide additional context like parameter interactions or usage examples. Baseline 3 is appropriate given the comprehensive schema.

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

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

The description clearly states the tool's purpose: '查询地域信息列表' (query region information list) based on billing method and resource type parameters. It specifies the verb (query) and resource (region information list), making the function unambiguous. However, it doesn't differentiate from sibling tools like DescribeZones or DescribeAvailableResource, which likely provide similar geographical information.

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

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

The description provides no guidance on when to use this tool versus alternatives. It mentions parameters but doesn't explain the context for querying regions, such as when setting up infrastructure or checking availability. With sibling tools like DescribeZones and DescribeAvailableResource that might overlap, the lack of differentiation is a significant gap.

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