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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description goes further by disclosing domain state semantics that annotations cannot express — the meaning of "confirmed" vs "pending" consent and the concrete consequence that reminders to pending recipients are silently blocked.

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?

Three short, front-loaded statements: purpose, then why (recipient_id for create_reminder), then a caveat about consent status. Zero filler, and the most decision-relevant sentence (routing) comes before the nuance.

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?

With an output schema present, return-shape details are unnecessary, and the zero-parameter surface means no argument documentation is owed. The description covers everything an agent needs: what it returns conceptually, when to call it, and how to interpret the consent field.

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 tool takes zero parameters, so there are no parameter semantics to explain and the schema cannot leave gaps. The baseline of 4 applies; the description correctly spends its words on results interpretation instead.

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 ("List care-recipients") and immediately defines the resource in plain terms ("other people this account can send reminders to"), which cleanly separates it from siblings like list_reminders, list_voices, and list_upcoming. An agent can identify the right tool without opening any schema.

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 names the downstream consumer and the condition that selects this tool: "Needed to get the recipient_id for create_reminder." It also supplies the domain prerequisite (only "confirmed" recipients can receive calls; "pending" ones are blocked), so the agent knows both when to call it and how to interpret the result before acting.

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