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

With zero annotations the description carries the full burden and does well: it discloses the top-level `is_fallback` flag (so the agent knows a requested date may be substituted), names the aggregation grain, and warns '⚠️ 机构版专属' — a real entitlement gate the agent must check before calling. It stops short of saying what happens on a non-institutional request.

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?

Three compact blocks — what it returns, when the user's question maps to it, and the institutional caveat — with the payoff line first and no filler. Field enumeration is terse slash-separated notation rather than prose.

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?

Output schema exists, so return-value explanation is technically redundant, yet the mention of the fallback flag and the theme-as-mainline interpretation adds interpretive value. For a two-param read tool the only real gap is failure behavior when the institutional entitlement is absent.

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 `date` (blank = latest) and `limit` (default 50, max 200) are already fully documented. The description adds only indirect hints (`requested_date` / `is_fallback` imply the blank-date behavior) and no limits or format detail beyond the schema, so the baseline 3 holds.

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 resource and scope up front: themes grouped from stocks making 100-day highs today, with the returned row fields named (`theme`, `plate_code`, `raw`). It also names the sibling `ashare_sector` as the gainers-list counterpart, so an agent can separate the two without opening a 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?

Gives an explicit trigger by quoting the user question it answers ('today which themes are hitting new highs / which sector has the most'), which is strong routing guidance. It suggests cross-referencing `ashare_sector`, but never states when NOT to use this tool or what the fallback path is for non-institutional callers.

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