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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds genuinely new behavior: results ordered most-recent-first, partial-name matching, the default league, and a cost of 1 credit — the credit cost in particular is not derivable from any structured field.

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?

Two tight sentences, front-loaded with the primary use case, followed by the parameter guidance and the cost note. There is no filler and nothing an agent must read past to act.

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 simple 3-parameter lookup with an output schema, the description covers purpose, matching behavior, ordering, league options, and cost. Minor gaps remain: it doesn't say what happens when the name is ambiguous or how many matches return against 'limit'.

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 coverage is 67%; the description adds meaning beyond the schema by clarifying that partial names work and that league switches between WNBA and college vs the NBA default. The 'limit' parameter is documented nowhere, which keeps this from a 5, though its min/max make it largely self-explanatory.

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 ('find a player's id by name') plus the matching semantics (partial names) and ordering, which distinguishes it from a detail-fetch sibling like get_player. It does not name get_player explicitly as the follow-up tool, so the id-lookup vs full-profile split is implied rather than stated.

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 to find a player's id by name' and 'Pass league for the WNBA or college' give clear operating context, including which cases require the league parameter. No explicit exclusions or named alternatives (e.g. when to use get_player instead), so it stops short of a 5.

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