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

Annotations already declare readOnly, idempotent, non-destructive, non-open-world, so safety is covered. The description adds genuinely new behavioral context: recurrence rules are expanded into concrete occurrences and merged into a single chronological timeline, which the agent cannot infer from annotations or schema.

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 purpose and the sibling comparison, then a compact Args note. Slight verbosity in the two-paragraph split, but every sentence carries information and there is no filler.

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-value explanation is unnecessary. Purpose, sibling routing, recurrence expansion behavior, and the single parameter's range are all covered for a simple read-only list tool.

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 0%, so the description must compensate. It documents the sole parameter's meaning plus the valid range (1-50) and default (10), which the schema does not state beyond the default. Good compensation for a single-parameter tool.

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 (show/list) and resource (next scheduled calls across all reminders) with explicit scope ('ALL reminders, in chronological order'). It directly names and distinguishes itself from the sibling list_reminders, so an agent can select correctly without reading 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?

Explicitly routes the agent: 'Answers "what's coming up?" better than list_reminders, because it expands recurring rules into actual upcoming occurrences.' This names the alternative and the condition that favors this tool, leaving nothing to inference.

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