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

It discloses substantive behavior beyond the annotations: Tuesday-to-Thursday mornings, holiday skipping for US zones, year-end freeze, founder blackout dates, and the UTC fallback when timezone is unknown. This is strong behavioral context, though it does not cover all operational details such as count behavior or date-range defaults.

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 and then adds necessary timezone fallback guidance. It is compact, with no wasted sentences; the final 'Read-only' is brief and not harmful.

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 read-only scheduling helper with an output schema, the description sufficiently covers purpose, scheduling exclusions, and timezone fallback behavior. The main remaining gap is that the after and count parameters are not explained, but the output schema handles return values.

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 low at 25%, so the description needs to compensate. It explains recipientTimezone well but leaves companyId, after, and count undocumented beyond their schema names, including the count maximum and after-date semantics.

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 clearly states the resource and scope: the next send windows for one recipient, including specific scheduling rules. It is specific and distinguishable by concept, but it does not explicitly differentiate itself from nearby siblings such as list_send_recipients.

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 gives useful conditional guidance for recipientTimezone, including what happens if it is omitted. However, it does not state when to use this tool versus alternatives, nor does it include explicit exclusions or preconditions beyond timezone handling.

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