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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so 'Read-only' adds nothing; however, the description contributes real value by enumerating the returned fields and the 4-character ID format, which matters because there is no output schema. Minor gaps remain (no mention of behavior when no calendars are connected, or ordering).

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 sentences, verb front-loaded, no filler. The only near-redundancy is the trailing 'Read-only', which merely echoes the annotations and costs almost nothing.

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?

With no output schema and no parameters, the description correctly compensates by listing exactly which booking settings come back, which is what an agent needs to decide to call it. It is slightly incomplete on edge cases (empty calendar list, ordering, whether IDs are stable across calls).

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. The mention of '4-character calendar IDs' describes returned data rather than inputs, which is useful but not a parameter explanation.

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 ('List every calendar connected to the receptionists') and enumerates the payload it returns (work hours, appointment length, buffer, timezone, double-booking, cancellation, 4-character IDs). This is clearly distinguishable from siblings like calendar_list_events, calendar_update_settings, and findCalendarSlots without opening a schema.

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?

'Call first for any calendar question' gives an explicit entry-point rule that tells the agent when to reach for this tool before others. It stops short of naming the alternatives or stating exclusions (e.g., that event listing lives in calendar_list_events), so it is clear context rather than a full routing map.

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