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

Annotations already flag destructive=true, idempotent=false and openWorld=true, but the description adds context annotations cannot: the result only proves Wapiworld accepted the send, not delivery; the message goes out immediately; each call sends another copy; and recording settings may retain the text. That is exactly the extra behavioral layer the lower bar asks for.

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?

Roughly three sentences, front-loaded with the usage trigger, then the delivery/repeat/recording caveats, then the exclusion. Every clause carries information an agent needs; nothing is padding.

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 structure needn't be restated, yet the description still clarifies what the return does and does not guarantee. Combined with full schema coverage and annotations, an agent has everything needed to call this correctly.

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%, so chatId, content and instanceId are already fully documented with formats, limits and confirmation guidance. The description adds no parameter-level meaning beyond the schema, so the baseline 3 applies.

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 precise verb+resource (send a WhatsApp message) and scopes it to the user's own Wapiworld numbers. Among a sibling set that is entirely read-only (get_instance, list_instances, show_project_overview, etc.), this is unambiguously the one outbound-write tool, so no sibling confusion is possible.

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?

'Use this when someone asks to send a WhatsApp message from one of their Wapiworld numbers' gives an explicit trigger condition, and 'Not for broadcasts or bulk sends' gives an explicit exclusion. Both when-to-use and when-not-to-use are stated without inference.

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