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

Annotations already declare readOnlyHint=false, openWorldHint=true, idempotentHint=false, and destructiveHint=false. The description adds useful context that the refund goes to the card and is restricted to eligible first-eSIM top-ups, but it does not disclose non-idempotency risks or authorization requirements beyond what annotations provide.

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?

Three short sentences, front-loaded with the core action and followed by input and return notes. It is efficient, though the final sentence 'Returns the refund result' adds little value.

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 financial mutation with no output schema and a required transaction_id, the description is minimally adequate. It omits eligibility details, error behavior, and idempotency context, relying on annotations for safety signals.

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?

Schema description coverage is 0% for the single transaction_id parameter. The description partially compensates by clarifying that the input is the transaction_id of an eligible top-up, but it does not explain expected format or how to obtain a valid ID.

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 states a specific verb and resource: refunding an eligible first-eSIM wallet top-up to the card. It is clear enough to distinguish from siblings like topup_with_saved_method and list_wallet_refunds, though it does not explicitly name alternatives.

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?

Usage is implied by the word 'eligible' and the required transaction_id, but the description does not explain eligibility criteria, when not to use this tool, or point to alternatives such as list_wallet_refunds or topup_with_saved_method.

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