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

Beyond the annotations (which only mark it non-read-only, non-idempotent, non-destructive), the description discloses concrete behavioral traits: immediate effect, no quota, a hard cap of 20 active reminders surfacing as 'limit_exceeded', and the exact 'invalid_payload' triggers (past time, >180 days ahead, empty text). That is precisely the kind of failure-mode context annotations cannot carry.

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?

Extremely dense with zero filler: purpose first, then the two key parameters, then the behavioral/limits clause. Every sentence carries operational information an agent needs before calling.

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?

The tool has an output schema, so return values need not be explained, and the description still flags the two error strings. Combined with annotations and the nested schema descriptions, an agent has everything required to invoke this correctly; the only soft gap is silence on the optional domain-linkage fields.

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?

The top-level `input` parameter has 0% schema coverage, but the nested properties do carry descriptions. The description reinforces the critical `fire_at_local` semantics (local wall clock, no zone, server converts) and adds delivery semantics for `text` ('delivered as written, on its own') that the schema states less directly. It says nothing about the optional `resume_id`/`vacancy_id`/`interview_id` linkage fields, leaving those 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?

States a specific verb+resource: 'Schedule a reminder for the user', which an agent can act on immediately. It does not distinguish itself from the sibling `create_reminders` (plural), `list_reminders`, or `cancel_reminder`, so the agent must infer whether this is the single-item or batch variant.

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 says the operation 'applies instantly, no quota', which hints that rationing isn't needed, but it gives no when-to-use context and never routes the agent between this tool and the clearly related `create_reminders` sibling. There are no prerequisites or exclusions stated.

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