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. Beyond that, the description adds genuinely useful behavior: results are scoped to today's active games only (a freshness/window constraint) and each game carries live state plus Sportsbook pricing. It doesn't mention call volume, rate limits, or what happens outside the four listed leagues.

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, front-loaded with the operation and scope, with the field enumeration and the sport-narrowing hint following. The field list is dense but each item sets agent expectations about returned data, so it largely earns its length.

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 single optional parameter, an existing output schema, and read-only annotations, this is complete: the agent knows the source, the leagues covered, the time window, the payload contents, and how to narrow by sport. Nothing needed for a correct first call 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?

Schema description coverage is 100% and the single sport parameter is documented with its allowed values and default. The description's "pass sport to keep one league" restates the schema rather than adding format or edge-case detail, so the baseline 3 is appropriate.

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?

It names a specific verb and resource — listing today's active NBA/NFL/NHL/MLB games from FanDuel Research — and enumerates the returned fields (status, clock, scores, win probabilities, TV, odds with market/selection ids). The one gap is that it never names a sibling such as fanduel_sportsbook_live_scores or espn_scoreboard, so an agent must infer the boundary from the field list rather than from an explicit contrast.

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?

"Use it for a live scoreboard with prices" gives clear selection context, and "pass sport to keep one league" tells the agent how to narrow scope. There is no explicit when-not guidance or named alternative, so the agent gets a positive signal but no disambiguation rule.

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