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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavioral facts beyond them: it takes no input and it requires the customer's 4OVER4 sign-in, which is an authentication precondition the annotations do not express. It stops short of noting balance freshness or rate limits, so it is not fully exhaustive.

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 purpose, then routing, then behavior, then example phrasings — a sensible order. The trailing customer-phrase list is somewhat verbose but earns its place by helping match real user utterances; otherwise the wording is tight.

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 zero-parameter read tool with full annotations and an output schema, the description supplies everything an agent needs: what it returns (balance plus earned and redeemed entries), the auth requirement, and routing to siblings. No material gap remains, and return-format detail is rightly left to the output schema.

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 tool takes zero parameters, so the baseline is 4; the description correctly states "Takes no input," removing any ambiguity about whether a customer identifier must be supplied. Nothing further about parameters is needed or possible.

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 and resource ("Shows the signed-in customer's 4OVER4 coins balance and history") and immediately clarifies what the resource actually is (reward points earned on print orders). It distinguishes itself from the nearest siblings by name, so an agent can route correctly without opening any schema.

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?

Gives an explicit trigger ("use it when someone asks about their coins") plus two named alternatives with the conditions that select them: loyalty_tasks for earning mechanics and search_knowledge for redemption rules. Both when-to-use and when-not-to-use are covered.

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