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

Annotations already cover read-only, idempotent, non-destructive and closed-world operation, so the description is free to add the genuinely non-obvious behavior: timezone-local computation, hard exclusion of venues with dead-domain or 404 websites, and the fact that results are limited to hours Num has verified. The remaining gap is that with no output schema, the return shape is never described.

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?

The key constraint (open right now, destination timezone) is front-loaded and each subsequent sentence carries real information – the dead-domain filter, the coverage caveat, and the sibling pointer. It runs slightly long with emphatic capitalisation, but no sentence is filler.

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 read-only, single-required-parameter lookup this covers the mechanics, prerequisites (verified hours), exclusion rules and the correct interpretation of a short list. Nothing an agent needs to call it correctly or report its results honestly 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 description coverage is 100% for all five parameters, including near, limit, category, destination slug format and bookable_only, so the structured field already does the work. The prose adds no parameter-level detail such as slug format or semantics of bookable_only beyond what the schema states, which is the expected baseline 3.

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 – places that are open right now in a destination – and immediately scopes it by timezone computation. It clearly contrasts itself with the full-directory sibling search_places, so an agent can distinguish the two without opening a schema.

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 names the alternative ('Use search_places for the full directory') and specifies when-not to use the result as a definitive answer ('never tell a traveller nothing is open'). This covers both routing and an important misuse case that no other field supplies.

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