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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely useful operational context not in annotations: the data sources (Sina + Eastmoney) and that it is keyless, i.e. no auth is required. It does not state freshness/latency or whether values are real-time vs. end-of-day, which is the remaining behavioral gap.

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?

Front-loaded with the core capability, then routing guidance, then source attribution. The list of example user utterances is longer than strictly necessary but does serve retrieval/routing value; no sentence is redundant 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 and no parameters, the description carries the burden of describing the return payload, and it does so well (index levels, change %, day range, turnover, breadth counts). It falls short only on freshness/output-format details and on whether a market-closed state is handled.

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 tool takes zero parameters, so there is no parameter semantics to explain and the baseline of 4 applies. Nothing in the description misleads about inputs.

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?

States a specific verb+resource ('overall snapshot of the Chinese A-share market') and enumerates exactly what's inside: headline index levels (Shanghai Composite, Shenzhen Component, ChiNext, STAR 50, CSI 300), change %, day range, turnover, plus limit-up/limit-down breadth counts. It is immediately distinguishable from index- or pool-specific siblings without opening any 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?

Explicitly routes the agent away from this tool for narrower needs: 'For the ranked pools use ashares_limit_up / ashares_limit_down; for market-wide margin financing leverage use ashares_margin_financing.' The trigger phrases ('how is the China A-share market doing', '涨跌停家数') also define when this tool is the right call.

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