yahoo_my_leagues

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

The readOnlyHint, openWorldHint, and idempotentHint annotations already indicate this is a safe, non-mutating lookup. The description meaningfully adds that it requires Yahoo authentication, that the response shape is from vendor documentation and is unverified, and that the payload shape should be inspected before relying on field names. This is strong added behavioral context for an agent.

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 fairly long, but the length is justified because there is no output schema and the nested return shape is needed. It is front-loaded with the core purpose, followed by structured sections: return shape, caveat, example, and auth. The vendor-documentation caveat is especially valuable and earns its place.

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?

Given there is no output schema, the description supplies a detailed, caveated return-shape blueprint and an example call. It also covers authentication, the approximate nature of the payload, and the downstream use of league_key. This gives an agent enough context to call the tool, understand the response, and recognize when further verification is needed.

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 already covers both parameters at 100% and explains gameKeys formatting, requiredness, and that bare codes mean the current season. The description adds a small example and clarifies the output is scoped to the authenticated user's leagues, but it does not materially enrich parameter semantics beyond the schema.

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 this as the endpoint for an authenticated user's leagues across one or more games, and emphasizes that it is the source of league_key. It distinguishes the tool by positioning league_key as the prerequisite for downstream league tools, which helps separate it from sibling tools like yahoo_my_games or yahoo_my_teams. A slight deduction because the opening is a noun phrase rather than an explicit verb ('retrieves', 'lists'), though the intent is 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 states that league_key is what every league tool below needs, giving a clear workflow signal: call this first to obtain league keys. It also explains that gameKeys drives which games are included and provides a concrete NFL example. It does not explicitly discuss when to avoid this tool or name alternatives, but the downstream-hint is useful context.

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