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

Annotations already declare readOnlyHint and openWorldHint, so the description is not obligated to explain safety, and it instead adds genuinely new context: the data source (the page's own __NEXT_DATA__ payload) and a concrete credit cost of 3. It does not cover what happens when a listing is missing or region-restricted, but the added cost and provenance detail is above the annotation baseline.

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 sentences, front-loaded with the resource, then the returned fields and cost. Every clause carries information; nothing is repeated from the schema fields or annotations.

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?

Without an output schema, listing the returned fields is the right move and the description does it well, and the cost disclosure is valuable. However, for a 4-parameter tool with half its parameters undocumented, an agent still lacks guidance on the tld/country_code interaction and cache behavior, so it is only minimally complete.

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 50%, so the description needs to compensate and it does not mention any parameter at all. Two parameters (country_code, cache_max_age) carry no schema description and no explanation in the description, and the relationship between tld and country_code is left entirely ambiguous for the agent.

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 ('product details for a Walmart listing') and enumerates what is returned: title, price, availability, seller, ratings, images, specifications. It's clearly distinct from walmart_search in practice, but the description never names or contrasts the sibling tools that could be confused with it.

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?

Usage is only implied: the required product_id makes it obvious this is a lookup-by-id tool for a listing already known. There is no explicit when-to-use or when-not-to-use statement, and no pointer to walmart_search for discovering an item id. The 3-credit cost is the only explicit decision aid offered.

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