validate_mobile_number

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

Annotations already cover readOnlyHint, idempotentHint, and openWorldHint, so safety and side-effect expectations are already disclosed. The description adds that the tool detects operator and telecom circle, which is useful context, but it does not discuss edge cases like invalid formats or not-found operators; this is acceptable but slightly limited for a validation tool.

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 compact and front-loaded: it opens with the core purpose, follows with a direct use-case sentence, and finishes with concise Args/Returns lines. There is no filler, repetition of the tool name, or unnecessary explanation.

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 single-parameter, read-only validation tool with 100% schema coverage, annotations, and an output schema present, nothing essential is missing. The description also states the relevant returned concepts (validation result, operator, circle), making it fully actionable for an agent.

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 input schema describes 'mobile' as a 10-digit number with or without +91/0, and the description's Args section only restates that. Since schema coverage is 100%, the description does not add meaningful semantic value 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 first sentence states a concrete action ('Validate'), a specific resource ('Indian mobile number'), and an additional result ('detect operator/circle'). This clearly distinguishes the tool from the many validate_*/lookup_* sibling tools and avoids any tautology or vagueness.

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 explicitly says to use this tool when validating mobile numbers for KYC or contact verification, which gives the agent a clear trigger condition. It does not enumerate when-not-to-use scenarios or alternatives, but the tool's narrow scope makes confusion with siblings unlikely.

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