Get free/busy schedule

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

Beyond the readOnlyHint/idempotentHint annotations, the description adds genuinely useful behavioral detail: it is read-only despite being an HTTP POST, the availabilityView character encoding (0-4), the inclusion of working hours and busy blocks, and the visibility caveat for subject/location. This is substantial context an agent would not get from annotations alone.

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 purposematic and then adding the encoding details and caveat. Every sentence carries essential information and there is no redundancy or 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 compensates by explaining the availabilityView encoding, working-hours return, busy blocks, and visibility behavior. It is slightly vague about the exact structure of 'visible busy blocks' but is otherwise sufficient for an agent to invoke and interpret the result.

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 parameters are already well-documented. The description reinforces some constraints (20 people, time window, interval characters) but does not add significant new parameter-level meaning beyond what the schema provides.

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 description uses a specific verb ('returns') and clearly names the resource: free/busy availability for up to 20 people or rooms over a time window. It also details the output format, making it easy to distinguish from calendar_list_events or calendar_get_event.

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 clearly establishes its context: checking free/busy availability for multiple people/rooms over a time window. It does not explicitly name sibling alternatives or exclusion conditions, but the purpose is distinct enough that an agent can infer when to use it, particularly against calendar_find_meeting_times.

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