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

Beyond the readOnly/idempotent annotations, it discloses that only the latest session is available, that a past date returns the latest session with a note rather than silently substituting, and that the source is a keyless public quote list. These are exactly the behavioral traits an agent cannot infer from structured fields.

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 purpose followed by constraints, and nearly every sentence carries operational information. It is somewhat dense with bilingual phrasing and example phrasings that could be trimmed without losing meaning.

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 the returned fields (code, name, last price, change %, volume, turnover) and noting the true total row count. Combined with the latest-session and exchange-coverage disclosures, an agent has everything needed to call it correctly.

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 date, sort enum values, and the limit range. The description adds framing (sort is descending, total row count always reported) but does not materially extend parameter meaning beyond the schema, 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?

States a specific verb and resource — a full-market latest-session board snapshot for SSE-listed A-shares — with concrete coverage (~2,358 stocks) and the exact fields returned. It is clearly distinguishable from siblings like ashares_index_bars and ashares_sector_flows by naming the board-level scope.

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 names the intended use case (running screens, momentum vs index, top movers) and the condition that makes it preferable to per-stock snapshot calls. It also states a clear exclusion — this is not a historical-date archive — and explains the SZSE limitation, routing the agent away from impossible requests.

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