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

Annotations already mark the operation read-only; the description adds the useful behavioral constraint that the salon is closed weekends and Czech public holidays. It does not cover edge cases like no availability or response format, but this is acceptable for a read-only lookup with annotation support.

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 sentences with no filler: the first states the core action and target, the second adds a relevant operating-hours constraint. All content earns its place and is front-loaded.

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 lookup tool with a fully documented schema and readOnlyHint, the essentials are present: date, services, optional hairdresser, timezone, and open days. The lack of an output schema and no explicit statement about the response format is a minor gap, but it does not prevent correct invocation.

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 coverage is 100%, so date, serviceIds, and optional hairdresserId are fully documented in the schema. The description mentions 'given day' and 'selected services' but adds no parameter-level meaning beyond what the schema already provides, matching the baseline.

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 action ('Find free start times'), a precise resource ('a given day for the selected services'), and implicitly differentiates itself from the confirm/request/list siblings by being an availability lookup. The working-hours sentence adds scope without blurring the purpose.

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 description gives clear context: it should be used to discover free start times for selected services on a specific date, and it notes closed days. It does not explicitly name alternatives or when-not-to-use cases, but the context is sufficient to distinguish it from the booking and list siblings.

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