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

No annotations are provided, so the description carries the full behavioral burden. It does disclose the return payload (overlap in UTC, per-zone local overlap, and each zone's working window) and the default 09:00-17:00 window, which is genuinely useful. It is silent on edge behavior — what happens when zones have no overlap, or when an invalid IANA zone is supplied.

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 short sentences, each carrying distinct content: what it does, what it returns, and the default assumption. The core purpose is front-loaded and there is no filler.

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 correctly takes on the job of describing return values, and it does so at the right level of detail for a 4-param tool. It stops just short of complete because ambiguous edge cases (no overlap exists, invalid zone input) are left unspecified.

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%, including formats, patterns, defaults, and the ordering constraint on workStart/workEnd, so the baseline is 3. The description's only parameter-adjacent content ('Default hours 09:00-17:00') merely repeats the schema defaults, adding no new meaning.

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 ('Finds the working-hours overlap of 2-10 zones on a date') with an explicit scope bound (2-10 zones). It also previews the return shape. It never names or contrasts the siblings convert_time and zone_info, so an agent must infer the distinction, but the purpose itself is unambiguous.

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?

Usage is implied by the narrow single-purpose framing plus the default working hours, which signals a scheduling/meeting-planning context. However, there is no explicit when-to-use, no when-not-to-use, and no routing to convert_time or zone_info for related tasks.

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