find_free_slot

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

With no annotations, the description carries the behavioral burden. It discloses that results are ordered earliest-first, already-past times are skipped, and slots respect working-hours boundaries. It does not explicitly state that the tool is read-only, but 'Find' and 'Returns' strongly imply it. Missing details about how existing events are considered are minor because 'open slots' conveys that.

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 short sentences with no wasted words. The core purpose is front-loaded, followed by the most decision-relevant behavioral notes (ordering, past-skipping, and the create_event handoff).

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 7-parameter schema with 100% coverage and an output schema, the description does not need to restate parameters or return formats. It gives the essential workflow and ordering behavior. It could mention the default search horizon and weekend skipping, but those are already in the schema, so the description 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 100%, so the schema already documents all seven parameters. The description only adds 'given length' and 'working hours', which map to duration_minutes and day_start/day_end. That is useful but not substantial beyond the schema, so the baseline 3 is appropriate.

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 states a specific verb and resource: 'Find open slots of a given length within working hours.' It clearly distinguishes this availability-search tool from sibling event tools like list_events and create_event by focusing on open slots rather than calendar records.

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: return earliest candidates, skip past times, and feed results into create_event. This implies the intended workflow. However, it does not explicitly state when not to use it or name alternatives, so it falls just short of a 5.

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