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

Annotations already declare read-only, idempotent, open-world, non-destructive, so the safety bar is covered. The description then adds genuinely new behavior: the 90-day window cap, the fact that the response reports the *actual* available window rather than the requested one, that current parameter history is never returned, and that official Chinese exchange notices override.

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?

Three dense sentences with the purpose front-loaded and no filler; the constraint and precedence notes follow in priority order. Slightly compressed to the point of being cryptic in the last clause ('official Chinese exchange notices take precedence'), which costs a point.

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?

No output schema exists, and the description does sketch the return scope (actual window, notice precedence), which helps. But with four parameters at 0% schema coverage, two of them (`product`, `exchange`) are left completely undefined, so an agent cannot confidently supply them from this description alone.

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 description coverage is 0%, so the description has to carry the load and only partly does. It explains `days` (requested window, capped, actual window reported back) and implicitly maps `topic` to the listed categories, but `product` (pattern-constrained code) and `exchange` are never mentioned at all.

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?

Names a specific resource (CEC published rule changes) and enumerates the covered topics: margin, price limits, position/opening limits, fees, delivery, listing. That is enough to separate it from siblings like recent_notices or contract_expiry, though the description never explicitly contrasts itself with them.

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 a hard usage constraint (window at most 90 days) and an explicit when-not ('never current parameter history'), which tells the agent this is historical/announcement data, not live parameters. It stops short of naming an alternative tool for live values, so it is not a full 5.

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