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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds value by detailing the return content (including the purchase link format), which gives the agent a concrete expectation of what comes back. No contradiction; no extra caveats needed for a simple read.

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?

A single, well-structured sentence that leads with the action and then lists the key return fields. Zero filler, front-loaded with the core purpose.

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?

The tool has a single parameter, an output schema exists (so return structure need not be spelled out), and annotations cover safety. The description covers all essential invocation details, including the expected data fields and the link format, making it complete for an agent to call 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% – the handle parameter has a description and an example. The description reinforces that the handle is used in the link template but doesn't add new semantic information beyond what the schema provides. Baseline 3 is appropriate.

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 uses a specific verb ('Fetch'), a clear resource ('single product document'), and the identifier ('by product handle'). It also enumerates the returned data (metadata, variants, in-stock sizes, price, purchase link), which sharply distinguishes it from siblings like products.items.check_stock or the search tools.

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 clearly states the use case: fetch a product by handle. It doesn't explicitly mention alternatives or when not to use it, but the context is unambiguous given the sibling list. Lacks explicit exclusions, so a 4 rather than a 5.

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