Cheapest Price

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's added value is the behavioral context: a live check, the marketplace set queried, US-only Best Buy coverage, and locale/currency resolution in the shopper's country. That is meaningful context beyond the structured fields, though it does not address latency, caching, or result freshness guarantees.

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?

The scope constraint (live, local currency, compare links) is front-loaded, which is good. However, the first sentence duplicates the title exactly and the second sentence restates 'lowest current price for a product' before adding new information, so the text is redundant rather than tight.

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?

For a three-parameter, read-only lookup with no output schema, the description explains what the agent gets back (a lowest price plus comparison links) and where it comes from, which is sufficient to call it correctly. Minor gaps remain around result freshness and whether a missing match is possible.

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 documents all three parameters, making 3 the baseline. The description adds only marginal nuance, notably that Best Buy coverage is US-specific (the one country where a second retailer joins), which slightly enriches understanding of the country parameter.

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?

Clear verb+resource: it returns the lowest current price for a product plus comparison links, and names the sources (eBay, Best Buy in the US, Amazon, local shops). It is unambiguous, though it has no siblings to differentiate from and the opening clause simply repeats the title verbatim.

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 implied rather than stated: 'checked live in the shopper's own country and currency' tells the agent the tool is for live, locale-aware price lookups, but there is no explicit when-to-use, when-not-to-use, or alternative path. With no sibling tools, the omission is less costly but the guidance is still only implicit.

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