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

Annotations only declare the generic mutation profile (readOnly=false, destructive=false, idempotent=false), so the description earns credit for disclosing real side effects: where the block surfaces (calendar, profile, Settings → Availability) and that booking pages stop offering slots for ooo. It omits conflict/overlap behavior and whether existing entries are affected.

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 front-loaded sentence that leads with the action and the two modes, then packs the visibility effects into a compact parenthetical. Dense but every clause carries information; no 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?

Return values need not be explained because an output schema exists, and annotations cover the safety profile. Still, for a 7-parameter mutation tool the definition is thin on validation rules, timezone handling for time ranges, and what happens when an ooo block overlaps existing bookings.

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 coverage is 71%, and the description adds one genuinely new fact — all dates/times are in the user's profile timezone. However, it leaves endTime and startDate (both undocumented in the schema) unexplained, and does not clarify how endTime relates to startTime or how 'date' interacts with startDate/endDate.

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 gives a specific verb ("Add") and two named resources ("time off" type ooo, "focus block" type focus), and scopes it to "the user's own" availability. An agent can distinguish it from availability.read/availability.delete by verb, though no sibling is named explicitly.

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 useful guidance for choosing between the two modes (ooo = whole days with booking pages blocked; focus = a day or time range shown only in the calendar), but says nothing about when to use this tool versus availability.delete, working_hours.update, or calendar.update.

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