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

No annotations are provided, so the description carries full burden. It discloses that off-season leagues are absent (not stale), that the call is FREE, and that the directory covers only active leagues. It doesn't explain rate limits or exact response shape, but covers the key behavioral surprises.

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?

The description is front-loaded with the resource definition, then the free cost, then filtering options, then usage guidance. Some phrasing is fragmented ('the ids /api/v1/sports/forecast ... and the fantasy league key on'), which slightly hurts readability, but overall efficient.

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 2-param, no-annotation, no-output-schema tool, the description covers purpose, scope constraints, cost, filtering, and usage scenarios. It lacks response format details and error semantics, but is largely complete for an agent to call correctly.

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 0%, so the description must compensate. It does so by naming the two parameters (league and name fragment, matching 'query' and 'league') and listing valid league values (mlb, nba, ncaab, ncaaf, nfl, nhl). It doesn't explain query syntax or partial matching rules in detail.

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 clearly states what the tool returns — a player directory of ids, names, teams, and positions — and specifies the scope ('leagues currently ON THE BOARD'). It doesn't explicitly differentiate from sports_board, but the resource is distinct enough to route correctly.

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?

Provides explicit 'Use this when:' guidance with two concrete scenarios (needing an id from a player name, enumerating a league's roster). It also explains the 'absent league returns zero players' behavior which clarifies expected outcomes.

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