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

Annotations already declare readOnly, idempotent, non-destructive, non-openWorld behavior, so the safety profile is covered. The description adds value beyond that with the pagination model and the Cloud-API-only applicability constraint, though it says nothing about response shape or cursor semantics beyond the param.

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 compact sentences, front-loading the core action and scope, then the applicability constraint and pagination. No filler or repetition.

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 read-only list tool whose annotations already carry the safety profile, the description covers scope, an applicability constraint, and pagination. With no output schema, it could say slightly more about what each listed group contains, but it is sufficient to invoke 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?

With 75% schema coverage, most params are documented in the schema, but the 'limit' param carries no schema description. The description's 'Paginated with limit / after' supplies that missing meaning, tying limit to pagination and pairing it with the after cursor, which adds real value over the schema alone.

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 ('List') and resource ('WhatsApp groups a phone number administers'), with a scope qualifier distinguishing it from group-scoped siblings like whatsapp_group_get or whatsapp_group_create. It does not explicitly name the closest alternative (profile_groups_list), so an agent must infer the boundary, keeping it short of a 5.

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?

Provides an explicit when-not condition by naming the incompatible case ('coexistence numbers can't use it') and scoping to Cloud API numbers. It lacks an explicit pointer to an alternative tool, but the usage context is clear enough to route correctly.

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