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

Annotations already declare readOnlyHint=true, openWorldHint=true, and idempotentHint=true, so the safety profile is covered. The description adds some context by claiming 'real prices and deposits' and calling the calendar 'the authority,' which hints at authoritative live data, but it doesn't go beyond that—no disclosure about output shape, pagination, or side effects, though none are expected for a read tool.

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 carry real content: the scope of the response and the ordering constraint relative to booking_intent. The phrasing 'what a shop sells TIME for' is slightly flowery and less direct than it could be, but it's compact and front-loads the core purpose before the usage directive.

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, 3-parameter tool with annotations covering safety and schema covering parameters, the description is nearly complete. It explains the service/openings relationship and the booking_intent dependency. The main gap is that it doesn't explicitly state what a call without `service` returns (services only, no openings), though the schema covers this.

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%, and the input schema already documents shop, day, and service thoroughly, including the day default and the meaning of empty openings. The description reinforces the conceptual mapping (services → prices/deposits, service → openings) but adds no syntax or format details beyond the schema, so the baseline 3 is appropriate.

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 title gives a clear verb+resource ('Find appointment times'), and the description specifies the exact scope: services with real prices and deposits, plus openings for one of them on a given day. It explicitly distinguishes itself from booking_intent by positioning the shop's calendar as the authority, so an agent can tell them apart.

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 explicit sequencing guidance: 'Read this before booking_intent.' It also explains why (the calendar is the authority on what exists). However, it doesn't contrast with other relevant siblings like shop_lookup or market_search, and it doesn't state when NOT to use it beyond the booking flow.

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