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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuine behavioral context beyond that: results are broken down by size and color and report one of four discrete shipping levels, which tells the agent what it is actually querying. Nothing on auth or rate limits is disclosed, but the bar is lower given 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?

Two sentences, no filler: the capability and the value domain come first, the prerequisite routing second. Every clause earns its place and the agent-facing information is front-loaded.

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, the description need not explain return shapes, and it doesn't waste space doing so. It covers purpose, granularity, output vocabulary, and how to obtain the required key, which is everything needed to invoke this one-parameter read 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% and the single parameter is fully documented as coming from a search result's products[].group_key. The phrase 'one product and color' hints that the rollup key encodes product+color, which slightly extends the schema's wording, but this is a marginal clarification rather than real added semantics. Baseline 3 applies when the schema carries the load.

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 (Fetch) and resource (Nike shipping availability), plus the exact granularity: per size, for one product and color. The named shipping-level vocabulary (HIGH, MEDIUM, LOW, OOS) pins down the return semantics, and the sibling tools (nike_product_details, nike_product, nike_search) are named so the agent knows this is not a lookup-by-name tool.

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?

Explicitly prescribes the prerequisite workflow: identify the item with nike_product_details or nike_product first, and notes nike_search is for finding products. This is clear context for when to reach for this tool. It stops short of any exclusions or when-not conditions, but there are no competing availability siblings to rule out.

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