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

Though annotations already cover the safety profile (readOnly, idempotent, closed-world), the description adds substantial behavioral context beyond them: it documents the error semantics for a non-trading date ("returns an error naming the latest trading day"), discloses exclusions (ETFs and untraded stocks omitted from rankings), notes who computed which fields, and states the attribution obligation under Taiwan's Open Government Data License.

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, and most sentences earn their place (conventions, error behavior, attribution). The first sentence is nonetheless sprawling, bundling counts, rankings, and methodology into one long clause rather than breaking it into scannable pieces.

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?

An output schema exists, so return values need not be described, and the description still covers everything else an agent needs: date semantics, error behavior, unit conventions (TWD, shares, _pct), market codes, language of names, and the attribution requirement. Nothing material is missing for correct invocation.

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% for both parameters, and the schema already documents the date default and the 1-50/default-10 limit. The description restates the latest-day default and that limit means rows per ranking but adds no syntax or format detail the schema lacks, so the baseline 3 is appropriate.

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 (Taiwan market summary for one trading day) and enumerates exactly what is returned: TWSE and TPEx value traded, up/down/flat company counts, and three rankings. It also differentiates from siblings by naming tw_list_institutional_ranking for institutional net buying, so an agent can tell them apart without opening schemas.

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 clear context: default is the latest day with quotes, and it explicitly routes the agent to tw_list_institutional_ranking for institutional net buying as an alternative. It does not, however, distinguish this from other likely-overlapping siblings such as tw_get_daily_trading, leaving some selection ambiguity.

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