find_my_leagues

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

With no annotations, the description carries the full behavioral burden and usefully discloses that no token is required and all data is public, which is exactly the auth context an agent needs before calling. It does not cover failure behavior (e.g. unknown username) or any rate limits, so it is adequate rather than rich.

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?

Purpose is front-loaded, followed by the critical 'start here / no token' guidance, then the args. The Args block is slightly verbose but justified given the schema carries no parameter descriptions.

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?

An output schema exists, so return values need not be explained. Given that, the description covers what an agent needs: what the tool produces, that it is the prerequisite for other tools, that no auth is required, and the meaning/format of both parameters.

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 0%, so the description must compensate, and it does: username is clarified as 'the display name you log in with' (not an id or email) and season is given a format example ('2026') plus the real default behavior ('current season'), which the schema's empty default string does not convey.

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 ('Look up') and exactly what is returned: the Sleeper user id, the leagues, and the roster id within each. This distinguishes it from siblings like league_info, roster, and standings, which all operate on ids this tool produces.

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?

'Start here. Everything this returns is what the other tools need' is an explicit, actionable usage directive that positions the tool as the bootstrap step and implies the other tools depend on its output. It lacks an explicit when-not/alternative clause, but for a root entry-point tool that guidance is largely unnecessary.

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