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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds value beyond that by disclosing the return structure (slots grouped by date, each with start/end) and the requirement that starts be handled as UTC ISO 8601. It does not mention result limits or empty-result behavior.

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 tight sentences: purpose, return shape, and downstream handoff. Zero filler and the most decision-relevant information (what it finds) is front-loaded.

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, the description usefully compensates by sketching the return format, and the 100%-covered input schema handles parameters. Minor gaps remain around pagination/limits and what happens when no slots exist, but nothing essential for calling the tool is missing.

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 every parameter including eventTypeId, duration, timeZone and bookingUidToReschedule is already documented in the schema; baseline 3 applies. The description adds only the cross-tool note about passing a slot's start in UTC ISO 8601, without elaborating on the reschedule or duration parameters.

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 free start times for an event type between two dates') plus the returned shape (slots grouped by date with start and end). No sibling tool overlaps this capability, so an agent can select it unambiguously.

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 situates the tool in the booking workflow by telling the agent to pass a returned slot start into create_booking or reschedule_booking, which implicitly defines when to use it. It gives no explicit when-not conditions or alternatives, but none are needed here since no sibling duplicates availability lookup.

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