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

The annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that results are 'grouped by competition with start times', which gives some return-shape context, but it does not discuss rate limits, data completeness, or regional restrictions. An adequate but not rich behavioral add-on.

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 tight sentences: the first front-loads what the tool lists and its output grouping, the second immediately states the routing purpose and parameter hint. No filler or redundancy.

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 list tool with full schema coverage, annotations, and an output schema, the description supplies the essential purpose, downstream routing, and grouping hint. It does not mention the state parameter or regional behavior, but that gap is minor given the structured fields.

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%, so the baseline is 3. The description restates the optional experience list ('yourway, head-to-head, player-combos, bullseye, player-podium or or-bets'), which is already in the schema, and does not explain the effect of the state parameter or default behavior beyond what the schema provides.

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 begins with a specific verb and resource ('List the events a FanDuel bet-builder experience covers'), scopes it to 'NFL and NBA games', and adds grouping and start-time detail. It is clearly distinguishable from sibling tools like fanduel_sportsbook_event or fanduel_sportsbook_events_status.

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 explicitly states the downstream use case ('Use it to find an event_id for fanduel_sportsbook_builder'), naming the sibling it feeds into. It does not cover when not to use it or list competing alternatives, but the primary routing condition is clear.

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