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

Annotations already cover the safety profile (destructiveHint=true, idempotentHint=true), and the description adds genuinely new behavior: per-fallback quota consumption ('each delivered fallback also consumes one call from the account's quota') and the default channel states. It does not explain what 'destructive' toggling-off actually does or what a null value means, leaving a small gap.

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?

Front-loaded with the core intent, then the always-attempted scoping rule, then the quota caveat. The Args block is efficient, with only mild redundancy between the prose defaults and the per-argument lines.

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 description covers defaults, quota cost, and call behavior. What's missing is the effect of null/omitted arguments on an idempotent, destructive-hinted setter, which an agent would want before re-invoking.

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?

With 0% schema description coverage, the description must carry the burden and largely does: it defines reminder_id's source (list_reminders), and explains both booleans as miss-triggered channels. The defaults quoted ('WhatsApp is on by default, email is off') add meaning beyond the schema's bare 'default: null', though the null-vs-unchanged semantics remain ambiguous.

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 opening line names a specific decision ('Choose what happens when a reminder call isn't answered') and the body scopes it precisely: the call is always attempted, only the follow-up channels are configured. This is clearly distinct from siblings like set_reminder_voice or set_skip_dates.

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 gives clear operating context — the call attempt is unconditional and only fallbacks are toggled — and points to list_reminders as the source of reminder_id. It stops short of naming alternatives or when-not to use this tool (e.g., vs. set_reminder_voice), so it is clear context without exclusions.

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