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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description goes beyond that by disclosing the return envelope {"pages", "free_busy"} and the underlying endpoint, which is genuinely useful since no output schema exists. It stops short of explaining pagination mechanics or how pages are traversed.

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: the purpose and scope lead, followed by the return shape and endpoint. No filler, no restatement of the title.

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 tool with full schema coverage and annotation-backed safety, the description supplies the key missing piece — the return envelope — in lieu of an output schema. Only pagination mechanics and the timezone requirement's rationale are left implicit.

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 (from, to, tzid, calendar_ids, include_managed) is already documented with format and behavior in the schema. The description adds no syntax or semantic detail beyond what the schema provides, so the 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 precise verb (read), resource (free/busy information), and scope (across the account's calendars over a time window). This clearly separates it from siblings like cronofy_read_events or cronofy_list_calendars, which surface events or calendar metadata rather than aggregated availability.

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?

The description describes what it reads but gives no guidance on when to prefer this over cronofy_read_events, nor any prerequisites (e.g. whether calendars must be connected). No alternatives or exclusions are named, so the agent must infer usage.

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