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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds two pieces of genuinely new behavioral context: the credit cost of the call and the fact that stats are derived from every plate appearance (a data-granularity claim the annotations cannot convey). Pagination and season-range behavior remain unstated.

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?

A single front-loaded sentence with the use case first and the cost last; nothing is wasted. The long metric enumeration is dense but each group (batting vs pitching) does real work distinguishing the tool's coverage, though it crowds out room for usage guidance.

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?

An output schema exists, so return-value explanation is correctly omitted, and the cost is disclosed. The remaining gap is scope: nothing says which seasons are returned or how far back the data goes, which matters for a season-by-season stats tool with only a player_id input.

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% and both parameters are documented in-schema, including the enum for league and the 'from search_players' provenance hint for player_id. The description adds no parameter-level meaning beyond that, so the 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-resource pair ('a player's season-by-season batting ... and pitching') and enumerates the exact metrics returned, which clearly separates it from aggregate siblings like get_team_stats and from per-event siblings like get_plate_appearances or get_player_games. It does not name a sibling explicitly, so it stops short of a 5.

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?

'Use for...' establishes the intended context, and the cost note ('Costs 5 credits') gives the agent a budget signal before calling. However, there is no when-not guidance, no stated alternative for per-game or per-pitch granularity, and no mention of season scoping, leaving the choice against get_player_games/get_plate_appearances to inference.

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