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

Annotations already declare readOnlyHint and openWorldHint, so the description adds value by disclosing the row shape (race count, race types, finished flag, current race) and the multi-country coverage. Pagination behavior is left to the schema rather than described.

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 core capability and return shape, then usage. The parenthetical country enumeration is slightly padded but justifies the open-world coverage claim.

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?

For a 10-parameter filtered list tool with an output schema and read-only annotations, this covers purpose, row contents, and main filter levers. It doesn't mention that country codes come from fanduel_racing_filters, but the schema already does.

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%, with each parameter documented including sort values and country code format, so the baseline is 3. The description only restates the filters ('filter by country, race type, finished or featured and sort by minutes to post') without adding format or interaction details beyond the schema.

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 concrete verb and resource (list tracks racing today) plus what each row contains, and the 'today' scope implicitly separates it from past-track siblings. It never names a sibling like fanduel_racing_track or fanduel_racing_past_tracks, so the differentiation is inferred rather than explicit.

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 explicit use cases: find a track code, or find the next race to post, and lists the filter/sort levers that support those tasks. It stops short of stating when to choose a sibling tool instead (e.g., single-track lookup or past tracks).

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