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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the description is not required to explain safety. It usefully adds two facts the annotations do not carry: the call costs 3 credits and it is available on every plan tier — both directly relevant to whether an agent should spend the call.

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?

Front-loaded with the outcome, then grouping options, then cost — a sensible priority order with almost no filler. The trailing fragments 'Costs 3 credits. Every plan.' are terse to the point of being telegrammatic but still parse cleanly.

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?

An output schema exists, so return-shape explanation is rightly absent, and annotations cover the safety profile. The gap is the required `dog` parameter: for a two-parameter tool, leaving the identifier format unspecified is the one thing an agent most needs to call it correctly. Everything else the agent needs is present.

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 50%: `by` documents its default, but `dog` has no schema description at all. The description compensates partly by clarifying that grouping axes can be combined ('track and distance') and enumerating the valid values, but it never says what `dog` expects — a name string, an ID, a slug — for the single required parameter. Baseline 3 fits given the schema does part of the work.

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: aggregate starts, wins and placings for one greyhound, with the grouping dimensions named. An agent can tell this is an aggregation tool rather than a raw-race/form lookup. However, it never distinguishes itself from the sibling greyhound_form, which sounds like the nearest neighbour and would leave an agent guessing which to pick.

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?

There is no statement of when to use this versus greyhound_form, horse_form, trainer_stats or track_conditions, and no exclusions or prerequisites. 'Grouped the way you ask' describes the mechanism, not the selection criteria. The agent must infer usage entirely from the title.

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