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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, so safety is covered. The description adds genuinely non-derivable behavior: results are sorted largest-to-smallest, fixed-amount discounts ($30 off) are deliberately excluded because they can't be ranked by percentage, and it enumerates the returned fields. It doesn't discuss pagination or empty-result behavior, so not a 5.

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?

Four sentences, front-loaded with the trigger condition, then output semantics, then the exclusion caveat. No filler or restatement of the title; every sentence carries new information.

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 an output schema present, return-value explanation is optional, and the description still summarizes the payload. Combined with annotations covering safety and a fully documented schema, an agent has everything needed to select and invoke this tool correctly.

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%, so the baseline is 3, but the description adds semantic framing the schema lacks: it maps natural-language user intent onto min_discount ("at least min_discount percent off") and category ("biggest beauty discounts"), clarifying that category is a restriction rather than a ranking modifier. limit is left to the schema.

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 (list) and resource (stores with the largest percentage discounts), plus scope details: sorted descending, threshold-filtered by min_discount, code-level data returned. It is immediately distinguishable from find_coupons (named store) and search_stores.

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?

It gives explicit trigger conditions with example user phrasings ("biggest beauty discounts", "codes for at least 30% off") and an explicit exclusion routing to a named sibling: "Do not use for a specific named store (use find_coupons)." That is the when/when-not/alternative trifecta.

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