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

Annotations already cover read-only and open-world behavior, yet the description adds real behavioral value: the all-or-nothing parameter contract throws on partial input, and the history branch is capped at a 366-day span. It stops short of describing return payload shape or pagination, so not a full 5.

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 dense sentences with no filler, and the two-branch structure is front-loaded. The backtick endpoint templates are compact but slightly cryptic for a caller who only needs argument behavior, which keeps it from 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?

With no output schema, the description only gestures at the return ('Predicted race times: the latest, or daily/monthly history'), leaving the prediction categories and response shape unexplained. It also references `{displayName}` path segments that are not among the three documented arguments, which may puzzle a caller. Adequate but with clear gaps for a read tool lacking an output schema.

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 67% and `type` has no description, but the description supplies the semantics the schema cannot express: the three parameters are an all-or-nothing group even though the schema marks zero required. That dependency is the single most important thing an agent needs and it is stated outright.

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?

Opens with a specific verb+resource ('Predicted race times') and immediately distinguishes the two retrieval modes (latest vs daily/monthly history). An agent can tell exactly what it gets and under which input shape without opening the schema.

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?

Explicitly states the trigger for each branch: no params hits `.../latest/{displayName}`, all three hits `.../{type}/{displayName}`. It also warns that a partial combination throws, which is effectively a when-not-to-use rule. No sibling alternative is named, but none of the sibling tools overlaps this capability, so the gap is minor.

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