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

Annotations already declare readOnly/idempotent/openWorld, so the bar is lowered, and the description still adds real context: the ranking heuristic used, auth mechanisms (X-API-Key / Bearer / x402 settlement after HTTP 402), and the signup requirement. It stops short of describing the returned offer shape or what happens when no trusted in-stock listing exists. The trailing meteora_brief pricing sentence applies to a different tool and slightly muddies the billing picture for this one.

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 purpose and the routing rule are front-loaded and efficient, but the closing block is boilerplate auth/signup/pricing text, including a sentence about meteora_brief pricing that is irrelevant to this tool. That material dilutes a description that would otherwise be two tight sentences.

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 simple single-parameter lookup, the description covers purpose, selection logic, and invocation requirements adequately. With no output schema, however, it gives no indication of what an "offer" contains (price, seller, listing URL, freshness) or how a null/no-offer result is signaled, leaving a meaningful gap for a recommendation 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?

Only one parameter and schema coverage is 100%, with the schema already giving a concrete example format ("product name + model or distinguishing keywords"). The description reframes it as a "product intent" but adds no syntax, matching behavior, or disambiguation guidance beyond the schema. Baseline 3 applies when the schema carries the semantics.

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 ("Return the single best current offer") and immediately defines the selection rule ("lowest price among in-stock listings the API trusts"). It also names the sibling it is not (search_products) for comparison use cases, so an agent can distinguish it without opening either schema.

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?

Explicit triggering conditions are given ("user asks where to buy something cheapest, 'best deal', or one clear recommendation") plus an explicit exclusion routing to search_products for side-by-side comparison. This is the when/when-not/alternative pattern in full.

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