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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. It states the tool 'Returns eligibility, regional limits, and the defining conditions,' which gives some output transparency, but it does not explicitly state that this is a read-only query, mention any side effects, rate limits, or error behavior. It adds moderate value but has gaps.

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 description is three sentences, front-loaded with the core purpose in the first sentence. It avoids fluff and clearly distinguishes the tool type, making it highly scannable and efficient.

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?

The description covers purpose, inputs, and outputs, but it says 'Needs nationality, the entry port/city, and whether they have an onward ticket,' implying all three are required, while the schema marks only nationality as required. This ambiguity about optional parameters is a gap. Additionally, there is no discussion of what happens when optional parameters are omitted, though the output description is helpful.

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%, so the baseline is 3. The description repeats the parameters ('nationality, the entry port/city, and whether they have an onward ticket') but adds no new semantic detail beyond the schema descriptions, which already explain the 'third country' condition. The description is consistent but not additive.

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 clearly states the tool checks eligibility for China's 240-hour visa-free transit, explicitly distinguishing it from the 30-day visa-free entry. This provides a specific verb (check) and resource (transit eligibility), and the exclusion sets it apart from any similar concept.

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?

The description gives clear context on what the tool does and explicitly excludes the 30-day visa-free entry, but it does not name alternative tools or provide when-not-to-use scenarios. The mention of required inputs (nationality, port, onward ticket) implies the typical use case, but explicit alternatives are missing.

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