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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful behavioral context beyond that: returned structured fields, the guarantee that prices are 'never guessed,' and explicit credit cost with free failed calls. It does not cover auth requirements or rate limits beyond the cost note.

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 short sentences, front-loaded with the core action and return fields. The cost and price-fidelity sentences earn their place. The marketplace sentence partially repeats the schema enum, but remains useful for framing the allowed pages.

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 appropriately explains the return fields and the price-fidelity behavior. It also covers cost and failure charging. A minor gap remains around behavior when a page lacks structured markup, but overall it is complete enough for a read-only extraction tool.

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%, so the schema already fully documents url, marketplace, and idempotency_key. The description only restates the marketplace enum values and adds no syntax or format detail beyond what the schema provides. Baseline 3 is appropriate.

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 specific verb and resource: 'Read one public product page and return the product data it publishes.' It lists the exact returned fields (name, brand, SKU/GTIN, offers with price, currency, availability), which makes the tool's scope obvious. It does not explicitly differentiate itself from generic siblings like scrape or from extract_contacts, so it stops short of a 5.

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 gives clear context for use: one public product page, with marketplace values for Amazon, Walmart, or Shopee pages. It also adds cost guidance. However, it never states when not to use this tool or names an alternative such as scrape for non-product pages, so exclusions are missing.

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