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

Annotations indicate readOnlyHint=false (mutation) and openWorldHint=true. The description adds valuable behavioral context by stating that numbers already used by other accounts are still valid, and specifically that it answers only the verified phone. It also highlights the verification requirement. No contradiction with annotations; it supplements them with meaningful details.

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?

The description is two sentences, concise, and front-loaded with the primary purpose. It packs in the prerequisite, parameter source, and an important edge case without unnecessary detail. Every sentence earns its place.

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 tool with only 2 parameters, no output schema, and clear annotations, the description covers the essential context: what the tool does, the prerequisite (owner verification), the parameter source, and a special-case behavior. An agent has all the information needed to call it 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 the parameters are already documented well (agent_id and phone_number_id with descriptions). The description adds the note 'Take phone_number_id from get_agent_whatsapp', which reinforces the source but doesn't significantly alter parameter meaning. It also adds the owner-verification context, but that's tool-level, not parameter-specific. Baseline of 3 is appropriate.

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 clearly states the action 'Connect a platform WhatsApp number to one of the account's agents', the resource (the number and agent), and the outcome (owner can message that number). It distinguishes itself from sibling tools like get_agent_whatsapp (listing) and detach_agent_whatsapp (removal) by focusing on the attachment action.

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?

It provides a clear prerequisite ('Requires the owner to be verified first') and tells the agent where to get the phone_number_id from ('Take phone_number_id from get_agent_whatsapp'). It doesn't explicitly say when not to use it versus alternatives, but the sibling detach_agent_whatsapp implies the opposite action, so the context is reasonably clear.

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