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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely useful context beyond that: ESPN's 'credential-free public JSON' tells the agent no auth is required, and 'it must be valid for the chosen sport' flags a cross-parameter validity constraint.

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?

Front-loaded with the core purpose, followed by the enum enumerations that earn their space by guiding valid invocation. The long inline league list is dense and there is a minor typo ('eSPN'), but nothing is wasted.

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 values needn't be described, and the description fully covers both required inputs plus routing to espn_team. It is adequate for a two-param read tool; only cross-sibling disambiguation is light.

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 coverage is 100%, so the baseline is 3, but the description adds real value: it enumerates the full league list (far beyond the schema's 'e.g. nfl, nba...') and states the cross-parameter rule that league must be valid for the sport, which the schema does not express.

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 and resource ('Returns the full team list') scoped to sport and league, and explicitly contrasts itself with espn_team ('Use espn_team to retrieve ESPN team detail'). An agent can distinguish it from sibling list/detail tools without opening either schema.

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?

Provides clear context and names the alternative (espn_team) for the detail case, and supplies the exhaustive sport/league values an agent needs to invoke it validly. It does not, however, mention the other ESPN list siblings (espn_standings, espn_team_roster), so exclusions are incomplete.

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