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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds value annotations cannot: the 3-credit cost and the fact that it is available on every plan tier — both operationally relevant before calling. It stops short of noting anything about result shape or volume for a whole field.

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, front-loaded with what it returns, then how to identify the race, then cost. No filler and no repetition of schema fields.

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 values need not be explained, and cost/plan coverage is stated. The remaining gap is that all five parameters are optional with no statement of what happens if none are supplied, which leaves a small ambiguity for an agent constructing the call.

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 60%; venue, race_id and meeting_date are documented in-schema, but `runs` and `race_number` are bare integers with only defaults/bounds. The description adds the important semantics that race_id and the venue+date+number triple are alternatives for identifying the race, but says nothing about what `runs` controls despite it being the one knob that shapes the output.

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+resource and scope: 'Recent runs and form stats for every runner in one race'. The 'every runner in one race' scope implicitly contrasts with the sibling horse_form (single horse), though it never names that sibling explicitly. An agent can tell what it returns 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?

Provides invocation routing ('Give race_id, or venue + meeting_date + race_number') and the cost/plan gate ('Costs 3 credits. Every plan.'), which is real guidance. However, it never says when to choose this over horse_form or race_card, nor when not to call it, so the when-vs-alternatives dimension is only implied.

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