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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description still adds real semantic context beyond that: the flags are source-catalog flags, not caller-specific location eligibility, and it explicitly enumerates what is not returned. That is genuine disambiguation, not a restatement of the 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?

Three short sentences, each doing distinct work: what is returned, how to interpret the flags, and what is excluded. The payload statement is front-loaded and there is no filler.

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?

With an output schema present, return-shape detail is unnecessary, and the description still supplies the interpretive caveat an agent actually needs (catalog flags vs. caller eligibility). For a zero-parameter read-only catalog tool, nothing material is missing.

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 tool takes zero parameters, so there is nothing for the description to clarify; baseline is 4. The empty object schema with additionalProperties=false is self-explanatory and the description does not waste words on inputs.

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 gives a specific verb and resource ('List the current public US-DK Daily Fantasy sport catalog') and quantifies the payload ('exact sport codes and DraftKings' enabled/public-contests flags'). It never names a sibling (draftkings_leagues, draftkings_featured_leagues, draftkings_pick6_sports), so the differentiation is by scope description rather than explicit routing.

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?

Usage is implied rather than stated: reading a catalog of sport codes for downstream use is obvious, and the negative scoping ('not contests, lineups, prizes, or account data') rules out several wrong expectations. But there is no explicit 'use this when… / use X instead' and no named alternative among the many draftkings_* siblings.

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