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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false, so safety is covered. The description adds meaningful context beyond that by noting it queries 'synced metadata', signaling results may be limited to locally synced contacts rather than a live server lookup.

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?

One sentence, front-loaded with the core purpose and followed immediately by the workflow hint. There is no redundant or filler text.

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 input schema, and an output schema handling return values, the description only needs to convey purpose and workflow placement — both of which it does cleanly.

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 100%, so query, limit, and account are all documented in the schema. The description's 'by name or number' aligns with the query param but adds no syntax or format detail beyond what the schema already says; baseline 3 is appropriate.

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 (Searches), resource (WhatsApp contacts), and scope ('synced metadata'), plus the matching keys (name or number). This is enough to separate it from generic siblings like search_contacts or whatsapp_list_chats without opening a 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 states the workflow: use it to resolve a person to their JID/number before whatsapp_send_message or whatsapp_create_group. It gives clear when-to-use guidance but does not state when NOT to use it (e.g., versus search_contacts or list_contacts), so it stops short of a 5.

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