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

Annotations already state this is not read-only and not destructive, and the description adds important context that the lookup is recorded in authenticated account history. That explains the non-read-only side effect and auth scoping, though it does not discuss idempotency or rate limits.

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 sentences, front-loaded with the primary use case and followed by the account-history side effect. There is no redundant or filler language.

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 one-parameter lookup with full schema coverage and an output schema, the description covers purpose, timing, auth context, and the recording side effect. Nothing essential for correct invocation 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 coverage is 100%, including an explicit South African mobile number example, so the schema already carries parameter meaning. The description adds only that the number is for a South African network, without additional format or validation details beyond the schema.

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 verb and resource: identify the South African mobile network for a number. It also scopes the purpose to airtime, data, or SMS prep, which separates it from sibling order-creation and SMS-sending tools.

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?

It gives a clear when-to-use condition: when the user needs the network before sending airtime, data, or SMS. It does not explicitly name alternatives or when-not-to-use cases, but the context strongly routes the agent away from create/send tools.

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