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

Annotations already declare non-read-only, non-destructive, non-idempotent, open-world behavior. The description adds value beyond them by disclosing the return payload (group id and invite_link), which is important with no output schema. It still omits permission requirements and the duplicate-group consequence of non-idempotency.

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?

Three short sentences with zero filler: action first, then return values, then the follow-up path. Every sentence earns its place and nothing is buried.

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 create mutation with no output schema, the description covers the return values and the next step for adding members, and the schema covers the required inputs. Missing only permissions/error behavior details, which keeps it short of a 5.

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 80%, so subject, description, profile_id, and phone_number_id are already documented in the schema. The description adds no syntax or constraint detail beyond what is structured, so the baseline of 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 specific verb and resource ('Create a WhatsApp group') plus the administrative scope ('administered by the phone number'), which lets an agent distinguish it from whatsapp_group_update and whatsapp_groups_list. It does not explicitly name a sibling as the non-alternative, so it falls 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?

It routes the agent for the post-creation step ('Add members with whatsapp_group_participants_add or share the invite link'), which is useful workflow guidance, but it never states when to prefer this tool over whatsapp_group_update or what input conditions select it. Usage is implied by the verb rather than stated.

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