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. Beyond that, the description adds real context: results are scoped to airport shops SkyBuyFly compares, prices are per shop, timestamps indicate when the code was seen, and an empty list is a definitive 'not sold' signal rather than an error.

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 sentences, each doing distinct work: what is returned, how to read an empty result, and what the tool is not. The output shape is front-loaded and there is no redundant restatement of the title or annotations.

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 needn't explain the response structure, and it is complete on scope, empty-result semantics, and the name-search exclusion. The only gap is the effect of the currency argument on returned prices, which is left entirely to the 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?

Schema coverage is 100%, so both parameters are already fully documented. The description corroborates the code by enumerating accepted symbologies and noting where the digits come from, but it never mentions the currency parameter or its default, so it adds only partial value over 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 names a specific verb and resource ('Find the SkyBuyFly product that carries a barcode') and defines the result shape: price per airport shop plus when it was seen. It also explicitly separates itself from name-based lookup with 'It does not search by name,' so an agent can distinguish it from search_products without opening a 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?

It gives a clear when-to-use context (a code read from a box or a photo) and a when-not condition ('does not search by name'), plus an interpretation rule for empty results. It stops short of naming the sibling tool an agent should use instead for name searches, leaving that inference to the caller.

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