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

With no annotations, the description carries full responsibility for behavioral disclosure. It states that the tool is FREE, that leagues appear only when in season ('on the board'), that absent leagues return zero players (honest answer), and that the ids are consistent with the paid forecast endpoint. This gives the agent clear expectations about cost, data currency, and edge-case behavior.

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 moderately long but every sentence adds value: it defines the directory, explains the 'on the board' logic, clarifies cost and id linkage, and gives explicit use cases. The structure is front-loaded with the primary purpose and ends with 'Use this when', making it easy to scan. It is not overly verbose, but could be tightened slightly.

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 lookup tool with no output schema and no annotations, the description covers the core information: what data is returned, when to use it, parameter meaning, and behavior for missing leagues. It implies a list of players but does not detail response format or pagination, which are not critical for this simple use case. Overall, it is sufficiently complete.

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?

The input schema provides zero parameter descriptions (0% coverage), so the description must compensate. It explains the 'league' parameter by listing valid values (mlb, nba, ncaab, ncaaf, nfl, nhl) and describes 'query' as a 'name fragment', implying partial match. This covers the essential semantics, though it could be more specific about case sensitivity or formatting.

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 identifies the tool as a sports player directory, specifying the resource (players) and the fields returned (ids, names, teams, positions). It distinguishes itself from siblings like sports_board (a board view) and fantasy_league (a league-specific tool) by focusing on player enumeration and ID lookup. The phrase 'on the board' adds context about league availability, making the purpose unambiguous.

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?

The description explicitly states when to use the tool: 'an agent has a player name and needs the id, or wants to enumerate a league's roster on the stat panel.' It also clarifies behavior for absent leagues (returns zero players). However, it does not mention alternative tools for when this tool is not appropriate, so it falls short of the top tier that names specific alternatives.

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