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

Annotations already declare destructiveHint=true and openWorldHint=true, so the safety profile is known; the description adds the crucial human-facing context that the message 'reaches a real person' and requires user confirmation, plus the PUBLISHED-only prerequisite. It does not mention rate limits or delivery/response behavior, keeping it just short of a 5.

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?

Two tight sentences, front-loaded with the core action and constraint, then the operational caution. No filler or redundancy.

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?

Covers purpose, precondition, and the human-impact caveat, with annotations supplying the safety profile and the schema supplying all parameter detail; no output schema exists so return values need not be explained. Only the lack of alternative routing leaves a small gap.

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 coverage is 100%, with descriptions for to, cta, body, flowId, accountId and idempotencyKey, so the schema carries the parameter burden. The description adds only the implicit PUBLISHED constraint on flowId and does not clarify optional fields like cta or body beyond 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 (send), resource (WhatsApp flow), and a binding constraint (PUBLISHED, single phone number), plus the delivery form ('a message with a button that opens it'). This is clearly distinguishable from create/publish/preview/list_whatsapp_flows siblings 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?

Gives a concrete precondition - confirm the recipient and text with the user before sending - which implies the when. However, it never names the natural alternatives (preview_whatsapp_flow for testing, send_message or send_broadcast for other channels), so the routing guidance is clear but incomplete.

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