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

Annotations already establish read-only, idempotent, non-destructive behavior, so the bar is lower, and the description still adds meaningful context: a tier gate ('Pro tier') and a data-freshness caveat ('~2019 data window') that an agent cannot infer from the schema. It does not discuss rate limits or result volume, but those are secondary for a read tool with an output schema.

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?

Front-loaded summary sentence followed by a compact Args block; every line adds a constraint or default. The 'Returns career wins, win rate, and per-venue breakdown' sentence is mildly redundant given an output schema exists, but it is short.

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 3-parameter read tool with an output schema and safety annotations, everything an agent needs is present: tier requirement, matching semantics, enum values and defaults, a numeric range, and the staleness of the underlying data.

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 0%, so the description carries the full burden and does: jockey_name is case-insensitive with partial matching ('mcdonald' matches 'James McDonald'), race_code enumerates 'gallops'/'harness' with a default and greyhound exclusion, and window is bounded at 14-365 days. The 14-365 constraint appears nowhere in the schema and is a genuinely additive detail.

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 track-by-track performance statistics for a jockey') and names the returned content (career wins, win rate, per-venue breakdown). The jockey-specific scope cleanly separates it from the sibling get_trainer_stats.

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 real usage conditions: Pro tier required, partial name matching supported, race_code defaults to 'gallops' and is unavailable for greyhounds, and window is an optional recent-form modifier. It stops short of routing between siblings (e.g. when to prefer get_runner_profile over this).

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