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

Annotations already declare the safety profile (readOnlyHint=true, destructiveHint=false, idempotentHint=true, openWorldHint=true), so the bar is lower. The description adds useful context beyond annotations: the data source (Eastmoney, keyless – implying no auth setup) and a full enumeration of returned fields, which is valuable for a read tool with no output schema.

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 core purpose is front-loaded in the first clause. It is somewhat dense with the long example-query list and the field enumeration, but each element carries informational weight and there is no filler.

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?

With no output schema, the description compensates by enumerating returned fields (code, name, price, change %, turnover, float cap, turnover rate, seal fund, seal time, industry, P/E). Source, scope, and trigger queries are all covered; only minor details like pagination/ordering behavior are left implicit.

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 description coverage is 100%, so the schema already documents both parameters (date format, limit range/default). The description adds nothing about parameter behavior or syntax beyond what the schema provides, so the baseline 3 applies.

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 states a specific verb and resource: the A-share LIMIT-DOWN board for a trading day, including the count of stocks hitting the down limit and the ranked list. It explicitly names the sibling it complements (ashares_limit_up), so an agent can distinguish it from related tools without opening the schema.

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?

It gives concrete triggering queries ('how many A-shares hit limit down today', '跌停家数', 'which stocks 跌停') and clarifies its role as the counterpart to ashares_limit_up for limit-up/limit-down breadth. It provides clear usage context but stops short of stating when NOT to use it or listing alternative tools for other breadth queries.

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