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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the full return payload, the dataset freshness date (2026-10-18), that no key is required, and a concrete rate limit of 50 free-tool calls per IP per day. The cost, freshness and quota disclosures are exactly the operational context annotations cannot carry.

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?

It is front-loaded with the usage trigger, then inputs and outputs, then caveats and cost – a sensible order. The bilingual disclaimer is duplicated in Chinese and English, which is repetition rather than wasted meaning, keeping it just below a 5.

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?

There is no output schema, and the description compensates by enumerating the returned fields and the specific exemption routes covered, plus validity dates and source links. For a single-parameter read-only lookup, nothing an agent needs to call or interpret it correctly is missing.

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?

With one parameter at 100% schema description coverage, the schema already documents that nationality is an English country name with examples. The description's "Inputs: nationality (English country name, e.g. Germany)" merely restates it, adding no format, normalization or fallback guidance, 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?

The description states a specific verb and resource – determining whether a passport holder can enter mainland China visa-free and for how long – which is immediately actionable. It does not explicitly differentiate itself from the sibling sample_eligibility, whose name suggests overlapping purpose, so it falls short of a 5.

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?

"Use when someone asks whether a passport holder can enter mainland China without a visa, and for how long" gives a clear trigger condition. There are no exclusions or named alternatives (e.g. when to prefer latest_regulation_changes), so it earns a 4 rather than a 5.

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