Busy blocks and free windows

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

With no annotations, the description carries the transparency burden and does a solid job, explicitly stating the merging behavior, the exclusion of free/transparent events, and that whole-day events block the day. It does not mention read-only behavior or return shape, but the core behavioral traits are disclosed.

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?

A single, information-dense sentence with a memorable opening phrase and no filler. Every clause contributes a meaningful detail about behavior or scope.

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?

The tool has six parameters and no output schema, so the description needs to cover key semantics and likely outcomes. It explains the busing rule, the free-window concept, and important calendar event behavior. It stops short of describing exact output fields or timezone handling, but those are partly covered by the schema.

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 only loosely maps to 'calendars named' and 'working hours', adding little 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 clearly states the tool's function: it returns merged busy blocks from selected calendars and free gaps within working hours. It also differentiates itself from calendar-listing or event-searching tools by focusing on availability windows and busy merging.

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 sets the context well: use this when you need to know where time is booked and where free windows remain within working hours. It does not explicitly name sibling alternatives or state when-not-to-use, so it misses full exclusion guidance.

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