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

Annotations already mark this as destructive and non-idempotent, and the description adds valuable context beyond those flags: the code is single-use and consumed, redemption grants Pro to the connected account, eligibility limits apply, and retrying a successful redemption is forbidden. This directly informs the agent about irreversibility and side effects.

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 every sentence carries operational weight: what the action does, who it affects, what prerequisites are absent, what limits apply, and what not to do. It is effectively front-loaded with the core redeem behavior.

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 tool with a 100% covered schema, an output schema, and annotations indicating destructiveness, the description provides all necessary context: target account, single-use behavior, eligibility limits, and retry guidance. Nothing an agent needs to call this correctly 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?

The schema fully describes the code parameter, including its pattern, case-insensitivity, and whitespace trimming, so schema coverage is 100%. The description adds only contextual instruction ('Use only a code the user supplied') but no additional parameter-level semantics beyond what the schema already provides, matching the baseline for high coverage.

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 identifies the verb ('Redeem'), the resource ('a gifted Pro or promo code'), and the effect ('grants Pro'). It also clarifies the target account ('the human account that connected this agent'), which distinguishes it from any room- or plan-scoped operations among the siblings.

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 gives concrete when-to-use guidance: only redeem a code the user supplied, no room or paid plan is required, and eligibility/one-per-account limits apply. It also explicitly says not to retry a successful redemption. It doesn't name an alternative tool, but the sibling list has no obvious competing redemption tool, so this is sufficient.

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