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

Adds real behavioral context beyond the annotations: per-call credit cost, the fact that repeated calls are billed again (consistent with idempotentHint=false), and a data-trust warning. It does not restate the readOnly/destructive hints, so the added value is genuine rather than duplicative.

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 short sentences, front-loaded with purpose, then cost, then trust warning. Nothing is wasted, though the cost sentence is slightly redundant ('actual cost follows your plan').

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 read-only metrics tool with a full schema and no output schema, the definition covers cost and safety but omits the one thing an agent most needs here: how this snapshot differs from the sibling shelf_trend/time-series tool. That gap keeps it at minimum-viable rather than complete.

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 the schema already documents all six parameters, including the compatibility-only newProduct field and the returnFields list. The description adds no parameter meaning beyond that, so the baseline 3 applies.

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 and resource: 'Retrieve listing-age distribution for a category.' An agent can tell it produces an age distribution for a category node, but the description never distinguishes it from the near-identical sibling amazon_market_shelf_trend, so the scope boundary is left implicit.

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?

No when-to-use guidance, no exclusions, and no routing to alternatives. With siblings like amazon_market_shelf_trend and amazon_market_performance present, the agent gets no help deciding which of these category-distribution tools to call.

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