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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: a $0.001 per-call x402 cost, weekend skipping by default, and a 14-day search cap. It stops short of saying what a payment failure looks like or how many windows are returned.

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, front-loaded with purpose then constraints then cost, with no filler. The 'up to 14 days' clause mildly duplicates the schema maximum, but the rest earns its space.

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?

An output schema exists, so return values need no explanation, and the annotations carry the safety profile. What remains thin is the x402 payment mechanic, which is named but not explained, and the unstated defaults for work hours.

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 coverage is 43%, so the description must compensate and only partly does. It clarifies that participants are optional and carry their own hours, and restates the weekend default and 14-day limit, but work_start/work_end defaults and the date-zone behavior are left entirely to the schema.

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 opens with a specific verb and resource: "Find when working hours overlap across time zones (meeting windows)." That is far more precise than siblings like timezone_convert or date_diff, though it never names an alternative tool to route away from.

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?

It implies usage through constraints (per-participant hours optional, weekends skipped by default, 14-day cap) but never states when to pick this over business_hours_deadline or timezone_convert. The agent must infer the selection rule from the sibling names alone.

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