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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations by disclosing the limited methodology (3 samples from one host) and that this is not a rigorous benchmark, which helps set expectations about data reliability.

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 slightly longer than a minimal two-sentence description, but every sentence serves a purpose: purpose, methodology caveat, and output format. It is front-loaded with the core action and uses structured formatting for the output specification, balancing detail with readability.

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?

Given the tool has only one parameter and no output schema, the description fully compensates by detailing the exact JSON array structure, field names, types, and meanings. It also includes a methodology note and reference link, providing complete context for an agent to understand the tool's behavior and results.

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% for the single 'capability' parameter, so the schema already documents the enum values. The description reinforces the meaning by saying rankings are 'by capability' and mentions 'capabilities' in the output, but does not add new syntax or additional meaning beyond the schema.

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 ('Get') and resource ('TrustBench liveness rankings for x402 providers by capability'), clearly distinguishing it from sibling tools which deal with receipts. It also states the output type (scored list with latency and success-rate telemetry), leaving no ambiguity about the tool's purpose.

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 implies usage for retrieving provider rankings by capability and even adds a methodology note (HEAD-probe checks, 3 samples) that cautions against over-interpreting results. However, it does not explicitly mention when to use this tool versus alternatives, though the sibling tools are clearly unrelated, making the context reasonably clear.

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