check_age_on_network

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

No annotations are provided, so the description must carry the burden. It discloses the primary behavior (returning the registration date) and adds an interpretive note about fraud risk, but it does not mention return format, error handling, or what happens for unregistered numbers. The fraud risk note adds context, but the disclosure is not comprehensive.

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 two concise sentences: the first states the exact purpose, and the second adds a risk-related note. There is no fluff or redundant information, making it efficient and well-structured.

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 one-parameter lookup with no output schema, the description adequately explains the return value and includes a useful risk insight. However, it omits details such as date format, behavior for invalid or unregistered numbers, and precise thresholds for 'very new,' so it is not fully complete.

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 covers 100% of the parameter descriptions, including 'Number to check.' The tool description does not add any additional parameter semantics beyond what the schema already provides, so the baseline score of 3 is appropriate.

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 tool's function: 'Return the date a number was first registered on the Safaricom network.' This is a specific verb and resource, and it distinguishes the tool from siblings like check_sim_swap, which checks a different aspect.

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 implies usage for fraud risk assessment with the note 'Very new lines carry elevated fraud risk,' but it does not explicitly state when to use this tool over alternatives or provide exclusions. No alternative tools are mentioned.

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