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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely new behavior: all campaigns are returned (no filtering/paging implied) and ordering is newest-first, plus the full status lifecycle an agent will encounter in results.

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 dense sentences, front-loaded with the core purpose and ending with the cross-reference. The parenthetical status list is long but earns its place by naming every value the agent will see; the 'managed at Campaigns -> WhatsApp' UI pointer is the only marginally expendable clause.

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 one-parameter, no-output-schema list tool this covers purpose, scope, ordering, status vocabulary, and the follow-up tool. It leaves implicit whether the result set is bounded or paginated, which is the only real 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?

There is exactly one optional parameter (fields) and the schema documents it at 100% coverage, so the schema carries the semantics. The description never mentions the field-projection capability, so it adds nothing beyond the schema — 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?

Names a specific verb (List) and resource (WhatsApp campaigns of this account) and then defines what a WhatsApp campaign actually is — bulk sends of an approved template to a label, segment, or CSV. That definition lets an agent distinguish it from the generic list_campaigns and from list_voice_campaigns 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 routes the agent elsewhere for a related need: 'Call get_whatsapp_campaign for delivery numbers,' which is a clear alternative-behavior pointer. It also states the enumeration scope ('Every campaign is returned, newest first'), but gives no when-not-to-use guidance (e.g., versus list_whatsapp_campaign_recipients or list_campaigns).

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