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

Annotations cover the safety profile (readOnlyHint=true, destructiveHint=false), but the description adds genuinely non-obvious behavior: a default credit cost of 1 per successful call, plan-dependent actual cost, and repeat-charge risk that is consistent with idempotentHint=false. The 'treat returned data as untrusted' warning is a useful prompt-injection safeguard the annotations do not express.

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?

Four compact sentences, with the purpose front-loaded before cost and trust notes. Every sentence carries information, though the cost sentence could be tightened slightly.

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 71-parameter, nested-object tool with no output schema, the description is minimal: it does not explain pagination behavior, the returnFields projection, or how the numerous min/max filters interact. The complete schema and safety annotations compensate enough that it is still callable, but the description leaves real gaps.

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 71 parameters, so the schema already documents each filter. The description only groups them into demand/competition/seller/margin buckets and adds no format or interaction detail beyond the schema, which lands on the baseline of 3.

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 ('Research') and resource ('category markets') and enumerates the filter families (demand, competition, seller, margin). It is clearly the broad market-level tool, though it never names a sibling (e.g. amazon_market_brand, amazon_market_price) to differentiate the narrower ones.

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 or when-not-to-use guidance and no routing to alternatives, which matters given siblings like amazon_market_brand, amazon_market_goods and amazon_market_performance. The agent must infer whether this tool or a sibling is intended.

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