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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description still adds genuine behavioral context the annotations cannot: the retention window is at least two years but variable, consumers must trust the returned startDate/endDate, and AVAILABLE vs NO_RANK_DATA encodes whether any weekly rank exists. It stops short of noting result-size limits or response shape, keeping it at a 4.

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-loaded with the scope, then routing, then field/status semantics — a sensible order with little waste. It does spend sentences defining searchFrequencyRank and searchVolume, which an output schema likely already carries, but the status-code gloss is not redundant.

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 two-parameter read-only tool with an output schema, this covers the non-obvious risks: variable retention, the authoritative date fields, and status meanings. Remaining gaps (pagination, result-size ceilings, per-marketplace coverage) are minor against the structured fields already present.

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%, with both parameters fully documented and marketplaceId enumerated, so the schema does the heavy lifting. The description only reinforces the 'exactly one search term' constraint already stated verbatim in the schema and says nothing additional about marketplace behavior or per-marketplace retention differences. 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: 'Return all retained raw weekly ABA observations for exactly one search term,' and draws a hard boundary against the sibling query_aba_search_terms. An agent can distinguish it from query_keyword_rank_trends and query_advertising_search_terms without opening any schema.

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: 'Use query_aba_search_terms for the latest report, share snapshots, and the recent 13-week trend,' and adds a negative exclusion ('Do not treat this as keyword-rank tracking or advertising performance'). Both the when-to-use and when-not-to-use cases are named against real siblings.

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