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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial behavioral context beyond that: the 14-day fetch window, business-hours restriction using schedulingStartHour/schedulingEndHour with 9 AM–6 PM defaults, and timezone auto-detection with UTC fallback. No contradiction with annotations; the read-only claim is consistent with a slot-finding operation.

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?

Roughly 100 words covering algorithm, defaults, timezone handling, and prerequisites — dense but every sentence earns its place, with the core purpose front-loaded in the first sentence. The googleAccountId defaulting is slightly redundant with the schema description but adds narrative clarity.

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 description covers the algorithm, window limits, business-hours semantics, timezone behavior, and account prerequisites, making it sufficient for correct invocation. The main gap is the return format, which is unstated and there is no output schema to fill it, though the slot semantics are reasonably inferable from the name and algorithm.

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 baseline is 3, and the description adds genuine value above it by wiring parameters into behavior: fromDate defines the search window, businessHoursOnly is tied to schedule hours and timezone fallback, and googleAccountId defaulting is explained narratively. This elevates the description beyond what the schema alone 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?

States a specific verb and resource ('Find the next available time slots in the user's Google Calendar') and goes further to describe the algorithm (fetch events for up to 14 days, return the first N gaps that fit the duration). The detailed behavioral description makes it easy to distinguish from the calendar create/update/delete siblings, and the free-slot semantics are clearly distinct from the similar-sounding check_calendar_availability.

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?

Gives explicit usage context: a prerequisite ('Requires a Google account to be connected and linked to the workspace') and clear defaulting behavior (googleAccountId falls back to the first connected account). However, it never names an alternative tool or states when NOT to use it, so the choice against sibling campaignstack_check_calendar_availability is left to inference.

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