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

Annotations already declare readOnly, idempotent, non-destructive and openWorld. The description adds genuinely new context beyond that: the data is 'live' from the calendar, times are in Asia/Bangkok, and results include the masters who perform the service. No auth or rate-limit caveats are given, but the added return/timezone context is substantive.

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 tight sentences, zero waste, with the core action ('Live free start times...') front-loaded before the optional filter and return shape.

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 carries the burden of describing return values and does so ('dates with times (Asia/Bangkok) and masters who do the service'). It could be slightly richer about the shape/grouping of results, but nothing essential for calling the tool 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%, so every parameter (date, days, staff_id, service_ids) is already documented. The description reinforces the optional staff_id ('specific master (staff_id)') and the multi-service capability, but adds no format, constraint, or default detail beyond the schema. Baseline 3 applies.

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 verb+resource ('Live free start times from the salon calendar') with the scope ('one or more services, optionally with a specific master'). It is clearly distinguishable from siblings like create_booking and list_services 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?

Usage is implied: this is the availability lookup you call before create_booking. But the description never explicitly says when to use it versus alternatives, nor does it state prerequisites (e.g. that services must come from list_services) or any when-not-to-use condition.

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