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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond those annotations: the result is time-scoped to today, the set is public and curated, and private challenge data is explicitly out of scope.

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 with no filler. The primary action and resource are front-loaded, and the important negative constraint is stated clearly in the second sentence. Every word earns its place.

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 zero-parameter read-only tool with an output schema and strong annotations, the description is complete. An agent has everything needed to know when to call it and what it returns, and the output schema handles return-value specifics.

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?

The tool has zero parameters, so the schema fully covers parameter semantics by construction. The baseline for zero-parameter tools is 4, and the description adds no unnecessary parameter-related noise.

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 uses a specific verb ('Return') and names a precise resource: today's public, curated either/or question set. It also explicitly distinguishes this tool from private challenge lookups, making it easy to differentiate from siblings like get_friendship_challenge and request_ballot_challenge.

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 phrase 'today's public, curated either/or question set' establishes a clear usage context, and 'No private challenge lookup' communicates an important exclusion. It does not explicitly name which sibling to use instead for private challenges, but the exclusion is strong enough guidance for an agent to route correctly.

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