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

Annotations already cover readOnly/idempotent/non-destructive, so the description wisely spends its budget on semantics: `date` is venue-local, `starts_at` is a full venue-local datetime to disambiguate post-midnight services, and an empty `slots` list means no availability rather than a closed venue. That last point materially changes how an agent reports results and is not derivable from any structured field.

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?

Front-loaded with the one-line purpose, then two tight paragraphs on date/slot semantics and empty-result handling. Every sentence adds value; slightly more prose than strictly needed, but no filler.

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 steps in to document the return shape (`slots`, `slot_id`, `starts_at`) and its empty-state meaning. Combined with annotation coverage of the safety profile, an agent has everything needed to call and interpret this tool.

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 0%, so the description carries the burden. It fully specifies `date` (venue-local, YYYY-MM-DD) but says nothing about `venue_id` format/source or any constraint on `party_size` (bounds, minimum). Partial compensation, so a mid score.

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 opening line states a specific verb (bookable times) and its exact scope: one venue, one date, one party size. It also names the sibling tool `book` as the consumer of the returned `slot_id`, so an agent can place it in the workflow without opening other schemas.

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?

It gives clear context (call this before booking, pass `slot_id` to book) and an explicit interpretation rule for empty results, including a retry instruction. It stops short of naming alternative siblings (e.g. `join_waitlist`) for the empty case, leaving that inference to the agent.

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