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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered without description help. The description adds content scope (variation theme, child ASINs), which is useful, but discloses nothing about auth, rate limits, or edge cases like non-variant ASINs. With annotations carrying the safety burden, a 3 is appropriate.

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 tight sentences, zero filler, and the core purpose is front-loaded ahead of the clarifying detail about what the tree contains. Every clause earns its place.

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-value explanation is not needed, and annotations cover the safety profile. For a simple one-required-param read tool, the description is essentially complete; the only gap is routing guidance against sibling ASIN-lookup tools.

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 100%, so all three parameters (asin, include_raw_rows, include_diagnostics) are already documented in the schema. The description adds no parameter-level syntax or format detail beyond 'for an ASIN.' Baseline 3 is correct when the schema does the heavy lifting.

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 and resource: 'Get parent/child variation relationships for an ASIN,' and clarifies the scope with 'variation family tree including variation theme... and all child ASINs.' An agent can immediately tell this is about variation families. It does not name or differentiate from any sibling (e.g. get_product_details, get_listing_registry), which keeps it from a 5.

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?

There is no when-to-use guidance, no exclusions, and no mention of alternatives such as get_product_details or get_listing_registry, which also touch ASIN-level data. The reader can only infer the call context from 'for an ASIN.'

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