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

Annotations already declare destructiveHint=true, idempotentHint=true, openWorldHint=true and readOnlyHint=false, so the safety profile is largely covered structurally. The description adds the partial-update constraint ('at least one is required'), which is useful, but says nothing about what an existing subject/description is replaced with, permission requirements, or failure modes — reasonable but thin given the mutation is flagged destructive.

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 short sentences with zero filler; the operation and its one hard constraint are both front-loaded and immediately actionable.

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 mutation tool with no output schema and annotations covering safety hints, the description is nearly sufficient: it identifies the mutable fields and the at-least-one constraint. It stops short of explaining the enum semantics or what happens to unspecified fields, which keeps it from being fully complete.

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 coverage is 67%, so the description must carry some weight. It names all three mutable fields and, importantly, adds the 'at least one is required' constraint that is NOT encoded in the schema's required list (which only lists the three identifiers). It does not explain the join_approval_mode enum values, which remain opaque in both places.

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 ('Change') and resource ('a WhatsApp group's subject, description and/or join_approval_mode'), naming the exact mutable fields. This clearly separates it from siblings like whatsapp_group_create, whatsapp_group_get, and whatsapp_group_delete, though it never names an alternative explicitly.

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 description gives one real usage constraint — 'At least one is required' — which tells the agent a call must supply a field to change. However, it offers no guidance on when to prefer this over sibling operations (e.g., join-request approval tools, participant tools) and no prerequisites or exclusions.

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