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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context: a concrete cost of 5 credits and the exact scope of the payload including per-90 rates and the last 10 matches, which tells the agent this is a heavy/expensive call worth caching.

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 dense sentence that front-loads the use case and then packs in the field inventory and credit cost with no filler. The long enumeration is justified because it tells the agent what data it avoids fetching separately.

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 and annotations covering safety, the description only needs to sell scope and cost, which it does. The one real gap is the absence of any pointer to get_player_games for broader match logs, given this tool already returns the last 10 matches.

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%, with both parameters documented and the league enum fully enumerated in the schema, so the baseline is 3. The description adds nothing about the parameters themselves, though 'one player' reinforces that player_id is a single ID rather than a list.

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 ('use for one player') and enumerates the returned data categories in detail, so the agent knows exactly what this fetches. It stops short of naming the overlapping sibling get_player_games, which also surfaces match-level data, leaving some ambiguity about which to pick for game logs.

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 one player' implies the single-entity lookup case, and the player_id schema field points at search_players for ID resolution. But the description gives no explicit when-not guidance and never acknowledges get_player_games or get_player_props as alternatives for adjacent data.

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