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

Annotations are minimal (readOnlyHint=false, destructiveHint=false, etc.), so the description carries the behavioral burden. It discloses side effects (appears in morning brief, email if enabled), the delivery_note caveat (won't actually deliver if cadence off), and date clamping semantics—all beyond annotation scope and consistent with them.

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 somewhat long but every sentence adds functional value: it opens with the core purpose, gives an example, then details each parameter and the return contract. Structure with Args/Returns aids scanning, though it could be slightly tightened without losing 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 non-trivial recurrence rules and a special delivery_note return case, the description covers everything needed for correct invocation: parameter constraints, recurrence behavior, return format, and a critical user-facing relay instruction. No output schema exists, but the return contract is fully described.

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 0%, so the description must fully document parameters. It explains text max length, frequency values with detailed recurrence rules (weekly on start_date's weekday, monthly day clamping, yearly month+day), start_date format, and end_date optionality—far exceeding schema titles.

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 states a clear verb ('Schedule'), a specific resource ('a reminder'), and concrete behavior ('appears in their morning brief...'), with an example ask. This distinguishes it from siblings like delete_reminder and list_reminders without needing to open their schemas.

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 explicitly provides a canonical usage example ('remind me every other Friday to pay child support') and explains where the reminder appears, which guides when to use it. However, it does not name alternatives or state when not to use it, so it stops short of the 'explicit when-not' bar.

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