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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds non-obvious context the annotations cannot carry — the historical depth (results go back to 2008) and the shape of each returned row. It does not mention pagination behavior despite page/limit parameters, which keeps it below 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?

Two sentences, both front-loaded with the highest-value information (what it returns, then the sibling handoff and date floor). No filler or repetition of the schema.

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 an output schema and complete parameter descriptions already present, the description supplies the remaining essentials: scope, historical floor, and downstream linkage. Minor gap is pagination/volume expectations for a per-track-per-day listing, but nothing that would cause a wrong 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 description coverage is 100%, so date, page, limit and track are already fully documented; the description only restates the track-vs-all-tracks dimension implicitly ("one track or every track"). Baseline 3 is appropriate since the schema does the heavy lifting.

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 ("List the races that ran on a past date"), the scope (one track or every track in FanDuel Racing), and even enumerates the returned fields. An agent can distinguish it from fanduel_racing_races (current) and fanduel_racing_past_race (single race detail) without opening a 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 names the downstream use: "Use it to find the race number fanduel_racing_past_race needs", which is a clear selection rule against that sibling. It does not state exclusions (e.g. when to use fanduel_racing_results or past_tracks instead), so it stops short of full routing guidance.

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