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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint, so the safety profile is fully covered. The description adds only mild context (verifying a recipient) and says nothing about return shape or error behavior. With annotations carrying the load, a 3 is appropriate.

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 tight sentences that front-load the purpose and then the use case. No filler, and the identifier scope is stated up front.

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 simple read with no output schema and full schema coverage, the description supplies enough to call correctly: what it fetches and the identifiers accepted. It could round out by naming the alternative resolver, but nothing essential is missing.

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, and the required user_id is described in great detail there. The description restates that the ID may be a provider user ID or phone-number identifier but adds no format or resolution detail beyond the schema. Baseline 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 (Retrieve) and resource (WhatsApp user profile) plus the accepted identifiers (provider user ID or phone-number identifier). An agent knows exactly what it returns. It does not explicitly contrast with sibling resolvers like messaging_resolve_recipient or whatsapp_list_contacts, 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?

"Use to resolve/verify the recipient before a new chat" gives a clear when-to-use context. However it names no alternative tools and no when-not-to-use conditions, which keeps it below 5.

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