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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false) and warn that results are not repeatable (idempotentHint=false). The description adds genuinely new context: a per-call credit cost, notice that repeated calls may charge again, and a prompt-injection warning that returned data is untrusted. It stops short of rate limits or pagination behavior, but the cost and trust disclosures are substantive additions.

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?

Front-loads purpose in one sentence, then compresses cost and trust caveats into short clauses with no filler. Slightly awkward phrasing ('1 account credits') is the only blemish in an otherwise tight, well-ordered description.

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 43-parameter tool with no output schema, the description covers cost and data-trust but says nothing about the response shape or pagination, and leaves ambiguous parameters such as queryType and historyDate entirely to the schema. Adequate given rich schema coverage, but not complete for a tool of this complexity.

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% across 43 parameters, including the marketplace enum and the nested sort object, so the schema does nearly all the work. The description only gestures at 'ASIN list' and 'market filters', which are already documented, adding no syntax, unit, or format detail beyond the structured fields.

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: 'Expand traffic keywords from an ASIN list with market filters', which tells an agent both what is produced and what input drives it. It does not distinguish itself from closely named siblings such as amazon_keyword_miner, amazon_traffic_keyword, or amazon_traffic_keyword_stat, so an agent cannot tell which to pick without opening schemas.

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?

The phrase 'from an ASIN list with market filters' implies the input shape but gives no explicit when-to-use guidance, no exclusions, and no named alternative among the many keyword/traffic siblings. The agent is left to infer selection criteria entirely.

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