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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered. The description adds genuinely new behavior: a 2-credit cost and availability on every plan — exactly the kind of metering/entitlement fact annotations cannot carry. No pagination or result-size notes, hence not a 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?

Three short clauses, resource first, then the shape cross-reference, then cost — front-loaded with no filler. Slightly terse to the point of leaving gaps, which is a completeness issue rather than verbosity.

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-value explanation is unnecessary, and the cost/plan line covers the main non-schema concern. However, with 4 parameters, 0 required, and only 25% schema coverage, an agent still cannot tell what 'name' or 'scope' filter or what default applies to scope, which is a meaningful gap for a lookup tool.

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 only 25% — just 'state' is documented in the schema, and its default rule ('AUS unless name is given') is the only semantic hint present. The description says nothing about what 'name' (trainer name filter?), 'scope' (metro/provincial/country/picnic) or 'season' do, so the four parameters are largely undocumented by both schema and 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 resource (Racing Australia trainer premiership tables) and anchors it to a sibling ('the same shape as jockey_stats'), which tells the agent the result shape without opening the schema. The verb is implicit (retrieve/list) rather than stated, and it does not say how it differs in content from jockey_stats beyond shape.

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?

The cost line ('Costs 2 credits. Every plan.') gives budget/entitlement context that informs when it is worth calling, and the jockey_stats reference implies the analogous use case. But there is no explicit when-to-use vs when-not-to-use guidance and no alternatives named for trainer data.

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