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

With no annotations, the description carries the full behavioral burden. It helpfully discloses the data source (Coinbase CDP Bazaar), result ranking ('relevance then cheapest first'), and pricing context (USDC on Base and other chains). But it omits auth/payment prerequisites, rate limits, and pagination, which matters for a paid-endpoint search.

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 and followed by the use case and filter dimensions. Minimal waste; 'the machine-payable web' is slightly editorial but does not bloat the definition.

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 6-param, all-optional search with no output schema and no annotations, the description covers provenance, purpose, filters, and ranking. It could say more about result shape and payment/auth requirements, but it is largely sufficient to invoke 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 83%, so the schema already documents host, chain, query, method, and max_price (including the unrecognized-asset exclusion). The description only restates the filter list without adding format or syntax detail, so the baseline 3 applies.

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 ('Search') and resource ('x402-payable HTTP endpoints'), and adds useful scope detail (25,702 endpoints, normalized from Coinbase CDP Bazaar). It is clearly distinct from search_mcp_servers and search_products by resource, though it never names a sibling explicitly.

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?

Clearly states the use case: find an API an agent can pay for per call and check its cost before calling. The filter dimensions (chain, method, host, max price) imply the selection context. No explicit when-not guidance or named alternatives, so it stops short of a 5.

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