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

Annotations already cover read-only, idempotent, and non-destructive behavior, so the description's added value is the Pro tier requirement, the conditionStats full-career vs ~2019 window scope caveat, and null sections below sample-size thresholds. Those are genuinely useful quirks not available in structured fields, though nothing is said about rate limits or failure behavior.

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 with purpose, then returned sections, then prerequisites, then caveats, then args — every line earns its place with no filler. The section list is dense but directly informs invocation expectations.

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 present, return format needn't be explained, and the description still covers scoping, null-ability, Pro gating, and parameter sourcing. The main residual gap is how window interacts with the ~2019 vs full-career scope split between stat groups.

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 must carry the load — and it does: runner_id's provenance (search_runner results) and window's meaning, units, and 14–365 range, none of which appear in the schema. It could go further on how window interacts with the default career window.

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 the full statistics profile for a runner') and enumerates the returned sections, which cleanly distinguishes it from siblings like get_jockey_stats and get_trainer_stats. An agent can identify the scope 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?

Explicitly names the prerequisite path: 'Use search_runner() first to find the runner ID', which routes the agent to the correct sibling. It does not state when-not to call it (e.g., for non-Pro tiers or when only recent stats are needed), so it stops short of full when/when-not guidance.

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