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

Annotations already cover the safety profile (readOnly, idempotent, closed-world), so the description's added value is the warning that coordinates and historical time zone rules — not today's UTC offset — drive downstream calculations. That is a genuinely useful behavioral nuance. It omits result-count limits and whether matches are fuzzy, which for a catalogue search an agent would want to know.

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?

Two tight sentences with zero filler; the resource and returned fields come first, the downstream-consumption caveat second. Every clause earns its place.

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 does well to enumerate the returned fields, and it flags the historical-timezone pitfall. But for a search tool it says nothing about result volume, ordering, or how to disambiguate multiple hits, leaving real gaps for the intended resolve-a-birth-place workflow.

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 0%, so the description must carry the parameter burden and it does not: nothing explains how 'query' is matched (exact, prefix, fuzzy) or that 'language' selects the returned name script, even though the zh-CN/en enum and default go unmentioned. The phrase 'Chinese and English names' is the only faint hint at the language parameter.

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?

Opens with a specific verb and resource ('Search Xiaodao's place catalogue') and enumerates exactly what a result contains (IDs, Chinese/English names, countries, first-level administrative areas). It implicitly separates itself from the sibling chart/calculation tools by naming them as downstream consumers, though it never states the contrast explicitly.

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?

'Select the intended place; its stored coordinates and historical time zone rules are used by the calculation tools' establishes the resolve-then-calculate workflow and gives the agent a clear selection instruction. There is no explicit when-not guidance (e.g. what to do when multiple matches return) and no direct naming of an alternative tool.

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