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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds genuinely new behavioral information not in any structured field — specifically what the response contains: dates, the GeNEVERsleep guide page, the count of listed events, and a sample of those events — which matters because there is no output schema. It omits ordering and how many nights are returned, keeping it from a 5.

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?

A single front-loaded sentence that leads with the resource and then enumerates what comes back. The parenthetical example list earns its place by disambiguating 'big nights,' and there is no filler. Slightly dense clause chaining ('with their dates, the ... guide page, the number ... and a few of them') is the only structural weakness.

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 three-optional-parameter read tool with full schema coverage, annotations covering safety, and no output schema, the description does the one job left to it: sketching the return payload (dates, guide URL, event count, sample events). Missing only horizon/ordering details, which is a minor gap rather than a blocker.

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%, so city, lang and per_night are already fully documented, including the enum values and the default of 5. The description only obliquely gestures at per_night via 'a few of them' and says nothing extra about city scoping or language effects. Baseline 3 is appropriate when the schema carries the semantics.

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 names a concrete resource ('the next big nights out') and grounds it with recognizable examples (Escalade in Geneva, Christmas nights, New Year's Eve), so an agent knows this is a curated seasonal/holiday listing rather than a general event feed. It stops short of explicitly contrasting with search_events or get_event, but the 'big nights' framing is distinctive enough to separate it from generic event lookup.

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?

Usage is only implied: the examples of Escalade, Christmas and New Year's tell the agent this is for headline/seasonal nights, not arbitrary event queries. There is no explicit 'use this when... instead of search_events' routing, no mention of whether it is time-bounded (how far ahead 'next' reaches), and no exclusions.

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