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

With empty annotations, the description carries full responsibility for behavioral disclosure. It reveals credit balance usage, OTT voucher redemption, the 7% merchant fee, the exact FUP allocation formula, and that buying tokens does not extend the subscription period. This is exemplary transparency, including edge cases like freemium conversion.

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 longer than average but every sentence contributes operational detail. The flow from purpose to mechanics to parameter documentation is logical. The @param lines at the end could be integrated or formatted more concisely, but no information is redundant.

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?

Given the presence of an output schema and the absence of annotations, the description thoroughly covers the tool's functionality, parameters, fee structure, and side effects (no subscription extension). There are no significant gaps for an agent to invoke this tool correctly, even among many sibling tools.

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?

Despite 0% schema description coverage, the description includes @param lines for customer_id, mobile, and ott_pin, explaining their meanings (e.g., ott_pin is a 10-digit number, mobile is typically the session_id). The prose also explains the behavior when ott_pin is omitted. This compensates fully for the schema's lack of descriptions.

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 it purchases additional subscription units, which distinguishes it from sibling tools that handle subscription payments (e.g., pay_subscription_with_credits). It also notes it works on freemium tiers, adding specificity about scope. The verb 'Purchases' and resource 'additional subscription units' are explicit.

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 its use for adding trial or add-on units, mentioning credit balances and OTT vouchers. However, it does not explicitly compare to alternatives or state when not to use it. The applicability to freemium is useful context but lacks direct exclusions or alternative tool references.

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