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

Annotations already declare destructiveHint=true, openWorldHint=true and idempotentHint=false, so the safety profile is covered elsewhere. The description adds nothing on top: it never warns that the card is delivered immediately to a live chat, that resending creates duplicates, or what a failure looks like.

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?

A single front-loaded sentence with no filler. It is efficient, though its brevity borders on under-specification for a six-parameter mutation tool.

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?

For a non-idempotent, destructive send operation with six parameters and no output schema, the description should say what the required instance_id/chat_id/phone_number triple represents and confirm immediate delivery. None of that is present, leaving meaningful gaps beyond what the annotations convey.

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 every parameter including the optional first_name/last_name/company fields is already documented in the schema. The description adds no meaning about how phone_number plus the optional name fields are assembled into the card, so the baseline 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?

The description states a concrete verb and resource ('Send a contact card'), which distinguishes it from payload siblings like whatsapp_send_location, whatsapp_send_file and whatsapp_send_poll without opening their schemas. It does not, however, explicitly name those siblings or the target chat semantics.

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?

There is no guidance on when to choose this over whatsapp_send_message or the other send_* tools, and no prerequisites such as needing a connected instance or an existing chat. The agent must infer usage entirely from the tool name.

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