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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile needs no restating. The description adds genuinely new behavior: search_term is a substring match, omitting it changes the result set to terms where the seller appears, and share data only exists for weeks where the term is in the seller's top three — a real data-availability caveat. It does not mention pagination or row limits.

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 tight sentences: what is returned first, then calling convention, then query intents. No filler and the most important scoping detail is front-loaded.

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?

There is no output schema, and the description adequately characterizes the returned fields (rank, click share, conversion share) and the coverage caveat. For a four-optional-parameter read-only analytics tool with annotation coverage, the remaining gap (row shape, week boundaries) is minor.

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%, so all four parameters are already documented and the baseline is 3. The description adds a little beyond the schema by specifying substring match semantics for search_term and the effect of omitting it, but says nothing about weeks (range/default), account, or marketplace_id.

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 resource and metric: Brand Analytics search frequency rank week by week, plus the seller's click share and conversion share on the term. The 'in each week they appear in its top three' clause ties it to a distinct data source, separating it from ad-side siblings like get_ads_search_terms and get_ads_search_term_verdicts.

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?

Gives explicit usage contexts ('is demand for this keyword growing', 'am I gaining share on this term') and states the two calling modes: pass search_term for one term, or omit it for the terms where the seller appears. It stops short of naming alternatives or exclusions (e.g. when to prefer get_brand_search_terms or the ads search-term tools).

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