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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so the safety profile is covered. The description adds real value beyond that: the return shape (ISO 8601 with the provider's offset plus a provider-local label) and the hard 31-day window constraint. It doesn't mention auth requirements, rate limits, or behavior for non-public/unknown services.

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?

Three short sentences, zero filler, with the core purpose front-loaded before the date and return-format details. Every clause carries information an agent needs.

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 correctly compensates by describing the returned start format. Combined with 100% schema coverage on the 5 params, an agent has enough to call it. Missing edge-case behavior (empty results, unknown slug/service, whether a non-public service errors) keeps it from a 5.

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 the baseline is 3. The description largely restates schema facts (YYYY-MM-DD format, 31-day max span), and the timezone/label behavior it mentions is already in the timezone parameter's own description. Only the ISO-8601-offset return detail is net-new, and that is a return-value concern.

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 ('Open start times for a public service') and scopes it to a public booking context, which implicitly separates it from the booking/mutation siblings like book_session. It stops short of naming any alternative tool explicitly, so an agent still infers the read-vs-write boundary rather than reading it.

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?

'using the same slot rules as the booking page' implies the intended context (checking availability before booking), but there is no explicit when-to-use/when-not or routing to book_session or get_provider. Usage is inferable rather than stated.

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