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

readOnlyHint=true is consistent with generating a link, and the description adds genuinely non-obvious behavior: geographic routing rules, the two destination numbers, and the constraint that this is WhatsApp only with no voice calls. However, the notes are framed as business context rather than disambiguating the generated link itself or what happens if location is absent or unmatched.

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?

Front-loaded with the action, then routing detail, then the usage trigger in a tight three-clause structure. The parenthetical town list and phone numbers are dense but functional; the embedded use-case sentence could have been its own shorter line.

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?

An output schema exists, so return-value explanation is not required, and the description covers the routing logic an agent cannot infer from structured fields. Missing only the edge case of an unmatched or missing location and whether the link is meant to be surfaced verbatim to the customer.

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 75%, which sets the baseline at 3. The description reinforces that 'location' drives Duncan-vs-shop routing and enumerates Garden Route towns, but it says nothing about customer_name or how message/product_context are folded into the prefill beyond the schema's own text.

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 artifact ('Generate a pre-filled WhatsApp deep link') plus the goal ('hand the customer off to the right contact'). This is clearly distinguishable from siblings like submit_enquiry or complete_checkout because the output is a deep link, not a form submission.

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?

Gives an explicit trigger: 'Use when the customer prefers human assistance or when self-serve checkout isn't appropriate.' That tells the agent when to reach for it, though it never names a competing sibling (e.g. submit_enquiry) as the alternative or states when not to use it.

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