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

Annotations already cover readOnlyHint, idempotentHint, and destructiveHint. The description goes well beyond those by disclosing DST-accuracy, the fallback behavior of returning 'null with the best partial coverage', and the detailed shape of the `friction` block including the `loneWolf` concept. This gives an agent a strong behavioral model of what the tool will compute and return.

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?

The description is front-loaded with the core purpose, then moves to the return contract, then to use cases. It is somewhat detailed, especially around return values even though an output schema exists, but the structure makes it easy to scan and every sentence contributes meaningful selection or behavioral 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 a tool with this complexity—5 parameters, 1 required, and an output schema—the description covers input scenario, algorithm behavior, return semantics, and practical use cases. The presence of an output schema reduces the burden for return-value detail, but the description is still complete enough for an agent to correctly select and invoke the 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%, so the schema itself already documents all five parameters. The description adds general context ('each participant's local working hours') but does not provide new parameter-level meaning beyond the schema. Baseline 3 is appropriate.

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?

The description names a specific verb ('find'), a specific resource ('the longest UTC window where everyone is simultaneously within their working day'), and a second distinct deliverable ('score the team's overall timezone friction'). It clearly distinguishes this tool from the sibling tools, none of which target meeting-window discovery or timezone friction scoring.

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 explicitly states the intended contexts: 'Useful for scheduling and for hiring/team-composition decisions.' It does not name alternatives or exclusion conditions, but no sibling tool appears to compete with this capability, so the absence of exclusions is acceptable.

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