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

readOnlyHint=true already establishes the safety profile, so the bar is lower. The description adds real context — the per-SKU aggregation, the optional review_count field, and wildcard filter behavior — but omits defaults and pagination behavior (page_size default 20 / max 100, since_period default year) that affect how results are read.

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?

Two tight clauses with no filler: the output shape comes first, then the filtering contract. The parenthetical listing of returned fields is dense but earns its place since there is no output schema.

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?

With no output schema, the description has to carry the return contract, and it does so only partially — it names products[] fields but not the pagination envelope or what the 'summary' flag adds (merchant/pagination info). For a 7-parameter aggregate endpoint that is a noticeable but not fatal gap.

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 only 57%, and the description fills the most important gap by documenting product_sku syntax (comma-separated, leading/trailing * wildcards) and the parent_product_sku alternative, neither of which has a schema description. It also clarifies the review_count flag is optional output. page and the since_period default remain untouched.

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?

The description names a specific resource and aggregation level — average star rating per product SKU — plus the return shape (products[] with rating, sku, review_count). That implicitly separates it from the review-level siblings (feefo_list_reviews, feefo_get_review), though no sibling is named outright and no verb is stated.

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?

It tells the agent how to narrow results (product_sku or parent_product_sku, comma-separated, wildcards) which implies the retrieval use case, but never says when to pick this over feefo_get_review_summary or feefo_list_reviews, and gives no exclusions or prerequisites.

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