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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses substantive behavior: the calculation honours opening hours, days off, spots, buffers, and existing Google Calendar entries, and results are returned in the business time zone. These are non-obvious traits an agent could not infer from structured fields. It still doesn't say what an empty result looks like.

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 sentences, front-loaded with the core computation, then a time-zone caveat, then the conditional partySize rule. No filler; every sentence adds 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?

For a read-only availability query with no output schema, the description supplies the inputs' effect, timezone, and capacity semantics. The main omission is the shape of the response (list of slot times? with resource/person names?) and what happens when nothing is available, which matters since there is no output schema to fall back on.

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%, so baseline is 3, but the description earns above that by explaining partySize's actual semantics: for partyMode 'tables' the slots are those with a fitting table, for 'seats' those with enough spots left. That meaning is absent from the schema's one-line partySize description. Other parameters (days, from, with, workspaceId) are left entirely to the schema.

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 resource and computation: free slots for a given service starting from a day, derived by applying hours, days off, capacity, buffers and existing Google Calendar events. An agent can distinguish it from list_appointments (existing bookings) and get_booking_settings (configuration), though the description never names those siblings explicitly.

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 by the purpose ('free slots ... from a given day'), and there is one conditional rule: pass partySize for restaurants and activities. However, there is no explicit when-to-use versus alternatives guidance (e.g. versus list_appointments or get_booking_settings) and no note on when availability cannot be computed.

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