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

Annotations already establish the safety profile (readOnlyHint, idempotentHint, non-destructive, closed-world), so the lower bar applies. The description adds useful behavioral context beyond those flags — that output is strictly historical/official results and explicitly not predictive or ranked — plus a clear statement of what the tool will not return.

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 short sentences with the core purpose front-loaded, followed by scope and provenance constraints. Every sentence carries distinct information and there is no filler or repetition.

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 one parameter, 100% schema coverage, and no output schema, the description compensates well by enumerating the returned fields (date, operator, prize tier) and clarifying the historical-only scope. An agent has everything needed to call it correctly and interpret the result.

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?

Single parameter with 100% schema description coverage, so the baseline is 3. The description only restates 'given 4-digit number' and adds no format guidance (such as leading-zero handling) beyond what the schema already provides in its own description.

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?

States a specific verb and resource ('Lists every official 4D draw in which a given 4-digit number appeared') plus the returned fields (date, operator, prize tier). This clearly separates it from siblings like get_latest_results, get_results_by_date and get_operator_results, which all key off date/operator rather than the number itself.

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 clear scope boundaries: 'Past winning appearances only, not a ranking' and 'Official results only; no number recommendations or forecasts' tell the agent when this tool applies and what it must not be used for. It does not, however, name a sibling as the alternative for lookups by date or operator, so routing between siblings is left to inference.

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