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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context beyond that: randomness comes from public drand and is externally verifiable, duplicates become two slices, and a shareable public results link is produced — though it doesn't say whether a persistent wheel record is created or whether spins can be repeated.

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 compact sentences, front-loaded with the action and outcome, with the verifiability and return-value notes following in logical order. The brand mention ('Perkadoo's Spin the Wheel') is mild filler but negligible.

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 two-parameter tool with no output schema, the description covers the essentials: what it produces (the landed slice), that a public results link comes back, and that results are independently checkable. Little an agent needs to invoke it correctly 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 coverage is 100%, so the baseline is 3; the description earns an extra point by explaining a semantic rule the schema cannot express — that a choice listed twice occupies two slices, i.e. weighting by duplication.

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 specific verb and resource ('Spin a wheel of choices ... land on one') and grounds it with concrete examples (a prize, a name, where to eat), which clearly separates it from siblings like pick_random_numbers or draw_winners that also produce random outcomes.

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?

The description makes the intended use case obvious through its examples, but it never states when to pick this tool over pick_random_numbers or draw_winners, and it gives no prerequisites or exclusions. Usage is implied rather than routed.

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