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

Annotations already mark this read-only, idempotent, non-destructive and closed-world, and the description adds real context on top: the rules are dated (2026), the scope includes options taken and explicitly what is *not* modelled, and official sources are included. That disclosure of gaps and provenance is genuinely useful for trusting the output. It does not say what form the answer arrives in (single document vs. per-topic sections) or how long it is.

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 sentences, no filler, and the second sentence carries the actionable routing instruction. The first sentence is a compressed list-of-contents ('the options they take') that reads slightly telegraphically, but nothing is wasted.

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 parameters, no output schema and a simple read-only knowledge lookup, the description covers what an agent needs: what it returns, its currency (2026), and its known-limitations section. The only remaining gap is the shape of the response, which matters somewhat given there is no output schema to describe it.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline applies. No conflicting or misleading parameter language is present.

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 identifies this as a reference/documentation tool: it returns 'the China rules the calculators apply (2026), the options they take, what is not modelled, and the official sources.' That is a clear resource plus a content inventory, and the closing sentence distinguishes it from the four calculation siblings. It is slightly meta ('what these calculators cover') rather than naming the verb directly, so it stops 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?

'Call it before answering a question the other tools may not cover' gives an explicit trigger condition and implicitly contrasts it with the calculation tools. There is no explicit when-not or ordered routing (e.g., use net_salary for a straightforward take-home figure), so the guidance is solid but not exhaustive.

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