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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the read-only nature is known. The description adds behavioral context about unknown outcomes: 'Unknown checkout or provider outcomes retain the original request and number,' which is valuable beyond annotations. It also reinforces the non-destructive intent with 'never start a replacement purchase.'

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?

The description is three sentences with no wasted words. It front-loads the core purpose, then adds a critical behavioral note. Every sentence contributes meaningful information, and the structure is clear and scannable.

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 tool with two parameters and no output schema, the description adequately covers what the tool does and a key behavioral nuance. It hints at distinct aspects (billing, assignment, activation) but does not detail the response format or enumerate possible statuses. Given the tool's simplicity and annotations covering safety, it is reasonably complete but could be more explicit about return content.

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 0%, so the description must compensate for parameter meaning. The description does not explain request_id or business_id beyond their obvious names, and it doesn't clarify their format or relationship. The names are self-explanatory, but no additional semantic value is provided, leaving the agent to infer.

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?

The description states a specific action ('Read an owner-authorized extra-number request') and clarifies the scope by noting 'Billing, assignment and live activation are distinct,' which differentiates it from related status tools. It also explicitly warns against starting a replacement purchase, distinguishing it from purchase/request actions.

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 provides clear guidance on when not to use this tool ('never start a replacement purchase') and implies that unknown outcomes should be checked here rather than initiating a new purchase. However, it does not explicitly name alternative tools like get_checkout_status or get_activation_status, so usage context is clear but lacks explicit exclusions.

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