request_number

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It merely restates the tool's name and adds the purpose 'SMS verification', but does not disclose side effects (e.g., reserving a number, deducting balance), required permissions, or the state change involved. The description provides no behavioral transparency beyond what the tool's name already implies.

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 a single, front-loaded sentence: 'Request a phone number for SMS verification.' Every word is necessary and there is no fluff. It is appropriately paced for a tool with a fully documented schema. This is a model of conciseness.

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?

Despite having a complete schema, the description lacks essential context for a request tool: it does not explain what the tool returns (e.g., a phone number and activation ID), what happens on success or failure, or any process steps (e.g., selecting a service first). With no annotations or output schema, the description is insufficient to understand the tool's full behavior.

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?

The schema description coverage is 100% (all 5 parameters have descriptions), so the baseline is 3. The tool description does not mention any parameters or add semantics beyond what the schema already provides. It neither compensates nor detracts from the schema, hence a baseline score.

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 clearly states the verb and resource: 'Request a phone number for SMS verification'. It distinguishes itself from sibling tools like get_balance and set_status by specifying the action of requesting a number for SMS verification. However, it does not explicitly name alternatives or contrast with other request-type tools, so it's slightly below a perfect score.

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 offers no guidance on when to use this tool versus alternatives. It does not mention typical scenarios, prerequisites, or exclude other tools. There is no explicit 'when to use' or 'use this instead of' information, leaving the agent to infer usage from the name alone.

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