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

Annotations already flag destructiveHint=true and idempotentHint=false. The description adds the crucial semantic behind that: the full seven-day payload replaces the prior schedule, and the change does not take effect until update_inbox working_hours_enabled is set. This meaningfully deepens the behavioral picture beyond the 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?

Three sentences, front-loaded with the action and its data shape, then the replace semantics, then the tool-pairing advice. No filler sentences; each one carries distinct information an agent needs.

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?

For a two-parameter mutation with a nested array and no output schema, the definition covers the encoding, the replace behavior, and the cross-tool dependency needed to make the change effective. Return behavior is not described, but with no output schema that is a minor gap.

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?

With schema description coverage at 0% for two parameters, the description must compensate, and it does: it explains the array carries one entry per weekday with the day_of_week convention, and that each day is closed_all_day, open_all_day, or an open/close time. inbox_id is left implicit but is self-evident from its name.

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+resource relationship ('Set the business hours of an inbox') and immediately scopes it with the domain model (one entry per weekday, encoding 0=Sunday…6=Saturday). An agent can distinguish it from update_inbox, which is explicitly named as the complementary tool rather than a duplicate.

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 clear operational guidance: send all seven days, the schedule replaces the previous one, and pair with update_inbox working_hours_enabled to apply it and out_of_office_message for out-of-hours messaging. It stops short of an explicit 'when to use this vs. X' exclusion, but the dependency framing is strong context.

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