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

Annotations already declare readOnly, idempotent, openWorld and non-destructive. The description adds real value on top: it discloses that it reads on-chain balances, that it returns tier and discount percentage per token, and notably that it never returns raw balance amounts (a privacy guarantee). That is meaningful behavior beyond the annotations.

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, then the return shape, then the cost note. No filler or redundancy.

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?

With no output schema, the description does the right thing by summarizing the return value (tier and discount percentage per token). The free/no-credit note is useful. It is slightly incomplete on how the seven wallet parameters interact (which one to supply), but overall adequate for the tool's complexity.

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 100%, so every parameter (merchant, and the per-chain wallet addresses) is already documented in the schema. The description adds no parameter-level syntax or selection guidance, so the baseline 3 applies.

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?

States a specific verb (Calculate) and resource (discount) with clear scope ('for a wallet at a merchant'), so an agent immediately knows what it returns. It does not explicitly name a sibling to differentiate from (e.g. wallet_trust, validate_code), keeping it at a 4 rather than a 5.

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?

There is no when-to-use or when-not-to-use guidance, and no reference to alternatives among the many sibling tools. The only usage-adjacent statement is 'Free: does not consume credits', which speaks to cost, not selection.

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