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

Annotations (readOnlyHint, openWorldHint) already establish the safe-read, open-world profile. The description adds the useful scope constraint that it fetches 'public' audiobooks only, but it does not disclose error behavior, rate limits, or availability constraints beyond that. With annotations carrying the safety burden, this is adequate but not rich.

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 with zero waste: the primary action and scope lead, and the routing guidance follows. No redundancy or padding.

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?

For a single-lookup product-detail tool, the description covers the resource, the identifier, and the returned facets, while annotations carry safety and an output schema covers the return shape. Nothing an agent needs to invoke it correctly is missing.

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 `asin` parameter is fully documented in the schema, including a format example. The description reinforces that lookup is 'by asin' but adds no syntax or semantics beyond what the schema already provides.

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') plus resource ('one public Audible audiobook by asin') and enumerates the returned facets (contributors, series, ratings, price, sample audio). This cleanly distinguishes it from siblings like audible_products (catalog) and audible_search (discovery).

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 routes the agent: audible_search to discover ASINs, audible_product_reviews for reviews, audible_product_related for recommendations, audible_series for series, and audible_products for catalog. Names both the alternatives and the conditions that select them.

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