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

Goes well beyond the annotations: it explains the consequence of non-idempotency ('calling it twice creates two reminders'), that it creates persistent state, that nothing fires on the due date, that a contact reply does not close it, and that assignment depends on key type (personal vs workspace). Annotations only flag idempotentHint=false and readOnlyHint=false; the description supplies the operational meaning.

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 action, then four tight clauses each carrying a distinct behavioral fact (persistence, non-idempotency, no-send, close semantics, assignment). No filler or repetition.

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?

No output schema exists, but the description covers what an agent needs: lifecycle, delayed/no delivery, closing rules, and ownership semantics. For a mutation tool with zero destructive hint and 100% schema coverage, nothing material is missing.

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 100%, with dueAt, contactId, reasonCode, reasonText and applicationId all documented in the schema, so the baseline is 3. The description's final sentence on key-scoped assignment restates behavior already covered by the applicationId schema description, adding no new parameter syntax or constraints.

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 and resource: 'Create a follow-up reminder for a person to get back to a contact.' It immediately distinguishes itself from the send/automation siblings by declaring it is 'a to-do, not an automation' and naming send_message and broadcast as the alternatives.

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 says when NOT to use it ('Nothing is sent when it comes due — use send_message or a broadcast to actually message someone') and clarifies it is distinct from the automatic 'no reply for N days' follow-ups. Both the routing condition and the exclusion are stated, not implied.

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