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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds value beyond that bar: it discloses a privacy guarantee ('Only a need category is stored, never your text') and cost ('Price: free'), both of which affect whether an agent should send sensitive text here.

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 compact sentences plus a cost tag, with the core action front-loaded. The mid-sentence 'or nothing yet' is slightly awkward inline but does convey useful empty-result behavior without bloat.

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 read-only, three-parameter tool with no output schema, the description covers purpose, privacy, and cost. The material gap is the undocumented 'limit' and 'max_price_usd' parameters, which matter for controlling result volume and filtering by price.

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 0%, so the description must carry the parameter burden. It maps loosely to the required 'need' string but never mentions 'limit' or 'max_price_usd', leaving two of three parameters with no meaning anywhere in the definition.

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 concrete actiondescribe a need in plain wordsand a concrete resultmatching goods on the x402 market, here or elsewhere. The tool's identity as a natural-language search over the broader market is distinguishable, but no sibling is named, so it stops short of the 5 tier.

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?

The phrase 'Describe what you need in plain words' implies the usage mode and 'or nothing yet' sets expectations for empty results, but there is no explicit when-to-use versus bazaar_list, niches, or wanted_board. Guidance is implied rather than stated.

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