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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful return context: start times are in Eastern and results include links to darimarket.us stats pages. It does not say what an empty result means (no games scheduled vs. data unavailable) or whether the response is sorted by time.

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?

A single front-loaded sentence that leads with the triggering user intent, followed by the payoff (matchup + Eastern start time) and the darimarket.us link detail. No filler, though the trailing link clause is slightly tangential to selection.

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 one-optional-parameter, read-only lookup with no output schema, the description covers the trigger, league coverage, returned fields, and timezone. The main residual gap is what defines "today" if the user's timezone differs from Eastern, and what an empty slate returns.

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 would be 3, but the description adds real meaning by expanding the enum in user-facing language ("college football" maps to the CFB value) and by listing all leagues, which signals that omitting the parameter yields the all-leagues view. The default behavior is thus clarified beyond the terse schema note.

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 states a concrete resource and scope: today's games across six named leagues, returning matchups and start times. It is immediately distinguishable from the siblings (player hit rates, player search, consistency rankings, article lookup), none of which deal with schedules.

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?

It opens with an explicit trigger ("Use when the user asks what games are on today or tonight...") and covers both the schedule and matchup/start-time intents. It stops short of naming alternatives or stating when not to use it, but the trigger is clear enough to route correctly.

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