Check free/busy

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds real behavioral value by disclosing the shape of the result — per-account busy periods plus a merged timeline — and the cross-account aggregation, which is meaningful given there is no output schema.

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, zero filler, and the return contract is front-loaded before the usage hint. Every clause carries information.

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 an aggregated free/busy query with no output schema, the description supplies enough about what comes back to call it correctly, and parameters are fully covered by the schema. It stops short of explaining merging semantics across timezones or how empty/overlapping periods are represented, which would matter for an aggregation tool.

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% and all five parameters (accounts, time_min, time_max, timezone, calendars) are documented in the schema itself, including the default-permission semantics for accounts. The description only restates the time-range notion, adding no syntax or format detail beyond the schema, so the baseline 3 applies.

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 ('Return the busy periods across accounts ... plus the merged busy timeline') with clear scope. It implicitly separates itself from detail-reading siblings via 'without reading event details,' but it never distinguishes itself from the very close sibling find_available_slots, which occupies nearly the same conceptual space.

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 a concrete usage context ('Use this to answer "am I free at 3pm?"') and an implied when-not ('without reading event details'), which steers the agent away from list_events/get_event. It does not, however, address when to prefer find_available_slots or find_cross_account_conflicts, both obvious adjacent tools.

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