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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, so the description need not repeat those. It adds value by specifying the exact data payload (manager-to-roster map, detected scoring format), and its 'downstream reads better' note implies a non-mutating, dependency-free operation. No contradictions with annotations.

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 sentences, zero redundant words. The first sentence front-loads the return payload; the second delivers a usage hint. No fluff.

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 read-only getter with one obvious parameter and strong annotations, the description covers the return payload and provides usage context. It doesn't detail error scenarios or distinguish from sibling getters, but those are not essential here.

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 sole parameter league_id is not described in the description, and schema_description_coverage is 0%. However, the tool name and 'One league's...' make the parameter's role obvious. Still, the description does not explicitly document the ID format or that it is required, relying on the schema pattern.

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 enumerates the returned league attributes (name, season, size, current week, scoring format, manager-to-roster map), making it clear this retrieves a single league's configuration. It distinguishes from sister tools like sleeper_find_leagues by focusing on a specific league rather than searching, though no explicit comparison is made.

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 phrase 'Everything downstream reads better once this has been called' indicates this is a preliminary/setup call to be used before other league operations. It does not explicitly mention alternatives or exclusions, but the context is clear.

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