market_searchFree. Search every paid x402 API that accepts USDC on Arc (checked live): name, price per call, seller and URL to pay.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Max results (1-25) | |
| query | Yes | What you need, e.g. 'web search' or 'token price' |
| Name | Required | Description | Default |
|---|---|---|---|
| total | Yes | Number of listings returned | |
| listings | Yes |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds valuable behavioral context beyond that: the search is free, checked live, and covers every qualifying API. This adds cost and freshness information not present in the annotations.
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 description is a single efficient sentence that front-loads the most important non-obvious facts: free, live, and comprehensive coverage. Every element earns its place, and there is no wasted wording.
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 relatively simple search tool, the description combined with rich annotations and a complete output schema covers the essential context: what is searched, what is returned, cost, freshness, and safety profile. Nothing critical is missing for an agent to invoke it correctly.
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 both 'query' and 'limit' are already documented in the input schema. The tool description does not add parameter-level detail, but it does not need to because the schema carries the full semantic burden.
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: 'Search every paid x402 API that accepts USDC on Arc.' It also lists the returned fields, making the tool's purpose concrete and easily distinguishable from the unrelated sibling tools.
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 description clearly implies when to use this tool: whenever the agent needs to find paid x402 APIs on Arc that accept USDC. It provides clear context but does not explicitly name alternative tools or exclusion conditions, though no sibling tool appears to compete with this search function.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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