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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered and the bar is lower. The description usefully discloses the card's contents (injury news, price-change progress, penalty-taker chance) since there is no output schema, but says nothing about data freshness, caching, or what happens when more than five names are supplied.

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 that opens with the use case before enumerating fields, so the agent gets the trigger first. It is dense but every clause maps to a real returned data point.

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 read-only lookup whose safety profile and parameters are fully covered by annotations and schema, the description is close to complete and compensates for the missing output schema by listing the card's fields. Minor gaps remain around horizon behavior, data recency, and how overflow beyond five names is handled.

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 'names' (1-5, max 15 items) and 'horizon' (1-8 gameweeks) documented in the schema itself. The description echoes the batch size but never mentions the 'horizon' parameter, so it adds no semantic value beyond the schema; 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?

The description states a concrete resource (FPL player card) and enumerates what it returns: expected points per gameweek, fixtures, injury news, price-change progress, ownership, xG/xA and penalty-taker likelihood. It implicitly separates itself from search/find/compare siblings by scoping to 'one to five players', but it never names a sibling tool explicitly.

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?

It gives a clear decision-making context ('whether to buy, sell or start them') and a batch-size constraint of one to five players, which is actionable guidance. It stops short of exclusions or naming alternatives such as compare_players or get_player_breakdown for narrower analyses.

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