x402_certs

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

With no annotations, the description carries the burden of behavioral disclosure. It states the core function (discovering subdomains) and the cost, but it does not mention whether the operation is read-only, any authorization requirements, rate limits, or potential error conditions. The cost detail is useful, but other behavioral context is missing.

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, concise sentence that is front-loaded with the purpose and includes the cost. There is no filler or redundant information, making it efficiently structured for quick agent comprehension.

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 tool with one parameter and no output schema, the description adequately conveys its purpose and what it returns (subdomains). However, it lacks details about the response format, pagination, or any limits, which would be helpful but are not critical for a straightforward lookup tool.

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 100% since the only parameter (domain) has a description 'Domain'. The tool description adds no additional meaning beyond the schema, so the baseline score of 3 is appropriate.

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 ('Discover') and names the resource ('subdomains from certificate-transparency logs'), which is distinctly different from sibling tools like x402_dns or x402_whois. It clearly communicates the tool's function without being a tautology of the name.

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 mentions the cost per call ($0.01 USDC/call), which implies a usage consideration, but it does not explicitly state when to use this tool versus alternatives (e.g., 'use x402_dns for live DNS lookups'). No exclusions or alternative routes are provided.

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