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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-structured behavior: when today's pick is undecided it returns the most recent pick instead, with its date. That fallback is exactly the kind of caveat an agent needs and cannot infer from annotations.

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?

Four sentences, front-loaded with the identity of the resource, then fallback behavior, then usage trigger, then return-field guidance. Every sentence carries information, though the final sentence packs two field explanations and a citation instruction into one line.

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?

With no output schema, the description must carry the return-value burden and largely does: it names listingUrl and url, explains what each is, and instructs the agent to cite listingUrl as the source. Combined with the fallback disclosure and usage trigger, an agent has enough to call and present the result correctly; only the absence of any sibling-avoidance note keeps it from being fully complete.

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; there are no argument semantics to explain. The description instead documents the two result fields, which is beyond the empty schema's reach.

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 directory's daily featured pick — and clarifies its identity in parentheses, which is distinct from get_trending, browse_category, search_listings. The verb/resource pairing plus the fallback clause makes the tool's scope unmistakable to an agent.

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 when a user asks for a recommendation of the day or something new to try" gives a clear triggering condition. It does not, however, name a competing sibling (e.g. get_trending) or state when this tool should be avoided, so it stops short of full routing guidance.

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