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

readOnlyHint already covers the safety profile, and the description still adds real context: the day boundary is UTC (so an agent knows which calendar day 'today' refers to) and the result is non-personalized and identical for all callers. It stops short of saying how or when the featured prompt rotates or whether it caches.

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 short sentences with no waste, and the resource identification is front-loaded before the UTC and universality qualifiers. Every clause adds a distinct, load-bearing fact.

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 with annotations covering safety and no output schema, the description supplies the timezone and determinism an agent needs. It could say more about what 'featured' means or what the returned prompt looks like, but nothing essential to invoking it 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?

The tool takes zero parameters, so the baseline is 4. The description correctly implies no filtering arguments exist by stating the result is the same for everyone, consistent with the empty schema.

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?

States a specific resource ('the featured prompt') with a temporal scope ('for today (UTC)') and a distribution property ('same for everyone'). An agent can tell this is a deterministic daily fetch rather than a random or user-specific pick, though it never names the sibling random_prompt it is implicitly contrasted with.

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?

'Same for everyone' and 'today' imply the usage context — call it for the shared daily pick rather than a random one — but no alternative tool is named and no when-not condition is given. Usage must be inferred from the contrast with siblings like random_prompt.

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