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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds two useful behavioral facts beyond that: the data is 'live' (freshly fetched rather than cached) and the JID must originate from a real source rather than being synthesized.

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 sentences with zero filler; the primary purpose comes first and the critical input constraint follows immediately.

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?

With annotations covering safety, a full schema, and an output schema that documents the return shape, the description is nearly complete. The only minor gap is failure behavior (e.g., what happens if the account is not a member of the group), which an agent might want to know.

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 both parameters are documented in the schema itself; the description's JID guidance largely restates the group_jid schema text. The optional 'account' parameter is not addressed in the description at all, so no value is added beyond the schema baseline.

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 ('Fetches') and resource ('WhatsApp group's live info + participant list'), and implicitly distinguishes itself from whatsapp_list_groups, which supplies the identifiers rather than the group details. An agent can tell what it returns without opening the 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?

The 'group_jid MUST be a group JID (…@g.us) from whatsapp_list_groups — never fabricate it' clause establishes the prerequisite discovery step and an explicit prohibition. It doesn't state when not to use this tool or name an alternative for metadata variants, so it stops short of full routing guidance.

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