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

Annotations already declare readOnly, idempotent, and non-destructive behavior, so the safety profile is covered. The description adds meaningful domain behavior beyond that: tokens are not money, cannot be cashed out or transferred, are limited to the issuing business, and memberships return only valid/invalid rather than a balance.

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?

Front-loaded with the core action and result, and each subsequent sentence adds return-shape or constraint information rather than filler. It is somewhat dense but nothing is truly 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?

With no output schema, the description carries the full burden of explaining returns and does so thoroughly: balance_cents, balance_hours, balance_points, reads_as formatting, and the valid/invalid membership case. An agent has everything needed to interpret the response.

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 coverage is 100% for the single 'code' parameter, so the schema already documents type and format. The description adds only human context ('the code printed on the card'), matching the baseline 3 where the schema does the heavy lifting.

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 action (return the remaining value) and resource (a closed-loop token: gift card, prepaid hours, membership, or points balance) and names the input (the printed code). It clearly distinguishes itself from siblings like lookup_business or list_business_offerings, which inspect the business rather than a token.

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 usage via 'Takes the code printed on the card' but never states when to choose this tool over alternatives or when not to use it. No sibling is named or excluded, so the agent must infer routing from the tool name and purpose alone.

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