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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description still earns credit for disclosing the pricing basis (each product's usual configuration delivered to the destination) and that checkedAt is the supplier's latest scrape. It says nothing about result volume, pagination caps, or what happens when a supplier lacks a product.

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 dense sentences: the first front-loads the triggering situation and the questions answered, the second supplies the pricing basis and field semantics. Nothing is repeated from the schema and no sentence is filler.

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?

An output schema exists and annotations cover safety, so the description need not explain return shapes. However, for an 11-parameter tool the omission of pricingTier semantics (base/tier1/tier2, which materially changes every price) and of currency defaulting behavior leaves real ambiguity that the schema alone does not resolve.

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?

With 36% schema coverage across 11 parameters, the description partially compensates by explaining versus (one supplier instead of all), category, and the destination basis of prices. It leaves limit, offset, search, currency, pricingTier, and categoryLimit undocumented, so an agent must infer the meaning of pricingTier and the pagination pair from bare enum names.

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 states a concrete resource (a supplier's prices) and a concrete output shape: how many products it is cheapest for, where it costs more, and by how much. It is clearly about whole-supplier rollups rather than single-product lookups, though it never names compare_product or get_supplier to make the separation explicit.

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?

"Use this when a seller asks how a supplier's prices compare overall, by category, or against one other supplier" gives three concrete triggering scenarios that map onto the category and versus parameters. It stops short of stating when NOT to use it or pointing at the sibling tools for per-product or supplier-metadata questions.

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