check_availability

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

Annotations already declare readOnlyHint=true, so the description's mention of 'Read-only' is redundant. However, it adds useful behavioral details like time format and default attendees, which are not in annotations.

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?

The description is three short sentences, each serving a purpose: purpose, time format, defaults. No fluff, front-loaded with the main action.

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?

Given the tool is simple, has an output schema (not shown but present), and operates in a calendar context, the description covers essential aspects. It could include more guidance on when to check availability, but it is adequate.

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 0%, but the description compensates by clarifying time format for start/end and default behavior for attendees. The interval parameter is not explained, but overall the description adds significant semantic value.

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 clearly states 'Free/busy over a window,' which specifies the verb (check availability) and the resource (free/busy info). It distinguishes from sibling tools like list_events and read_event by focusing on availability, not on event details.

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 provides context on time format ('naive local') and default attendees ('just you'), but it does not explicitly state when to use this tool versus alternatives like check_availability before create_event. The read-only hint is implied.

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