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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered by structured data. The description adds no behavioral context beyond that — no not-found/error behavior, no note on which identifier takes precedence when both are supplied, and no hint about result shape.

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 front-loaded sentence with the lookup keys stated immediately; there is no filler and nothing extraneous to remove.

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?

An output schema exists so return values need not be described, and annotations carry the safety profile. However, for a lookup tool with an anyOf/optional-parameter design, the description omits practical details such as fallback behavior when one key is absent — it is adequate but thin.

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 description coverage is 50% (gtin documented as 'EAN ili interni kod', id undocumented). The description clarifies that either key may be used and expands gtin to EAN/GTIN, which is slightly more than the schema's annotation, so it lands at the baseline for partial coverage.

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 pair (fetch details of a single product) and states the two accepted lookup keys, ID or EAN/GTIN. It is clearly distinguishable from the plural sibling search_products, though it never names that sibling explicitly.

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?

Usage is only implied: 'one product by ID or EAN/GTIN' suggests a direct-identifier lookup rather than a search, but there is no explicit statement of when to use this over search_products or fetch, and no prerequisites or exclusions are given.

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