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

With no annotations, the description carries the burden of disclosing behavior. It discloses the return format and field list, which is useful. However, it does not mention potential pitfalls like date range coverage, data update frequency, or error behavior. It provides basic transparency but lacks richer context.

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 extremely concise, with the main purpose front-loaded and parameters/returns presented in a clear, structured list. Every line adds necessary information without redundancy.

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?

For a simple data-retrieval tool, the description covers the essential aspects: purpose, parameters, and return fields. It lacks clarity on default date range when no dates are supplied and on data update behavior, but these are minor gaps given the tool's simplicity and the presence of an output schema.

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?

Schema coverage is 100%, so the baseline is 3. The description adds value by explicitly noting that 'trade_date' and 'start_date'/'end_date' are mutually exclusive ('二选一'), which is not enforced in the schema. It also restates parameter formats clearly.

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 identifies the tool as returning daily index data, specifically for the Shanghai Composite Index by default. It distinguishes from sibling tools like 'daily' (stock data) and 'etf_daily' by specifying '指数' (index) and the default symbol. The 'Returns' section confirms the data resource.

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?

No guidance is provided on when to use this tool versus alternatives such as 'daily' or 'etf_daily'. The description only states parameters and returns but does not mention exclusions or compare with siblings. The usage context is only implied by the tool name and description.

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