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

With no annotations, the description carries the behavioral burden. It discloses the dataset size, provenance, normalization, and ranking behavior ('ranked by relevance then cheapest first'), which is meaningful beyond the schema. It does not explicitly state that no actual API call is made, but 'before calling it' and 'Find a paid API' imply search-only behavior.

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 two tight sentences with no filler. The first sentence establishes the exact resource and data source; the second explains use, filtering, and ordering. Everything earns its place.

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 search tool with six optional parameters and no output schema, the description covers source, purpose, filters, and result ordering. It does not spell out the exact result shape, but the promise that the user can 'see what it costs before calling it' implies the output includes pricing. A short note about result fields would make it fully complete.

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 coverage is 83%, so the baseline is 3. The description mentions the filterable dimensions (chain, HTTP method, host, maximum price) and relevance-based ranking, but does not add significant meaning beyond the schema's own parameter descriptions. The 'limit' parameter lacks a schema description, and the description also does not elaborate on it, so no added value there.

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 ('Search'), a concrete resource ('14,793 x402-payable HTTP endpoints'), and a clear purpose ('find an API an agent can pay for per call'). It also names the data source (Coinbase CDP Bazaar), which distinguishes it from sibling tools like search_mcp_servers and search_products.

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 explicitly says when to use the tool: to find a paid API an agent can call with x402 and to see costs before calling. It also lists supported filters. It does not explicitly name sibling alternatives or state when not to use it, but the x402/HTTP-endpoint scope makes the intended usage clear.

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