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

Annotations already cover the read-only, open-world profile, so the lowered bar is met. The description still adds real context beyond annotations: races are returned 'newest first' and each race includes conditions, finish position, post-race report and starting price. No pagination or rate-limit detail, but the ordering behavior is valuable.

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 sentences, front-loaded with the returned payload before the usage/prerequisite note. The field enumeration is dense but each element is informative; 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?

Output schema exists, so return values needn't be re-explained. The description covers purpose, ordering, prerequisite id source, and rough content shape — enough for an agent to call correctly. Minor gap: no hint about how page/limit interacts with the 'newest first' history.

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 100%, so the schema already documents id, page and limit thoroughly. The description's note about fetching the horse id from fanduel_racing_search duplicates the schema's own id description rather than extending it, and page/limit are left to the schema. Baseline 3 applies.

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 ('Get a horse's FanDuel Racing career') and enumerates exactly what's returned: starts, wins, top-three finishes, win percentage, and past races with conditions and finish position. It distinguishes itself from list-style siblings like fanduel_racing_past_races by being horse-centric, though it doesn't name that sibling explicitly.

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 a clear use case ('study a horse's form') and names the prerequisite source ('needs a horse id from fanduel_racing_search'). It stops short of stating when to prefer this over related siblings such as fanduel_racing_past_races or fanduel_racing_results, so no explicit exclusions.

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