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

Annotations already establish readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description then adds real context beyond that: slotToken is signed, expires in ~30 minutes, must be passed back verbatim, must not be reused across venues, and an empty times array means genuine unavailability rather than failure. However, it doesn't cover return ordering, pagination, or rate limits. With annotations carrying the safety profile, a 3 is fair – meaningful additions, but the token lifecycle is the only substantial behavioral disclosure.

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 tight paragraphs, front-loaded with scope, then routing, then the token contract. Every sentence carries information; there is no filler or repetition of the tool name.

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 compensates by describing the returned payload (`at` label and `slotToken`) and the empty-array edge case. Combined with full schema coverage and annotations, an agent has everything needed to call this correctly.

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 and the schema already documents all four parameters with constraints (days 1-14, the rejected 'next Tuesday' phrasing, the slug format). The description adds some framing (serviceId comes from get_venue, tokens are per-venue), but not enough beyond the schema to lift this above 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 verb and resource (free appointment times), pins the scope to one venue, one service, up to two weeks, and names the audience (salons, clinics, studios). It explicitly distinguishes itself from the sibling find_table_times, so an agent can route 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?

Gives the alternative by name and the condition that selects it ("Use find_table_times for a restaurant instead") and states the prerequisite ("Needs a service id from get_venue"). Both the when and the when-not are explicit.

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