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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals ranking methodology ('unique payers weighted above raw call volume'), scope ('every service in the public index'), and access limits ('Free tier returns the top 5; full results... available as paid endpoints'). This is strong, specific behavioral transparency.

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 core purpose and key behavior are front-loaded in the first sentence. Subsequent sentences add valuable context about scope and limitations. The final sentence about a weekly report is tangential to invoking the tool, causing a slight deduction.

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 two-parameter search tool with no output schema and no annotations, the description is quite complete: purpose, ranking, coverage, and rate limits are covered. It does not describe the result format, but the search intent and limits make this acceptable.

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 the baseline is 3. The description does not add meaning beyond the schema; it only reiterates the capability search concept already captured by the query parameter description.

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 uses a specific verb ('Search') and resource ('live x402 services') with a clear scope ('by capability' and 'Covers every service in the public index'). It does not explicitly distinguish from the sibling x402_market_stats, but the purpose is unambiguous.

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 establishes the intended use case: searching services by capability, with ranking context. It does not explicitly mention alternatives or when not to use the tool, but the scope and capability focus provide clear context. Absence of sibling differentiation keeps it from a 5.

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