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

Annotations already convey readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds meaningful domain-specific disclosure by clarifying that the tool 'only reports payment terms' and explicitly denies signing, submitting, or settling payments, which is valuable context beyond the generic read-only annotation.

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 concise sentences: the first states the action and target, the second preempts misuse by stating what the tool does not do. Every word earns its place; no filler or redundancy.

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 zero-parameter, read-only tool with rich annotations and no output schema, the description is sufficient. It identifies what will be reported ('payment terms') and rules out side effects. An agent has everything needed to call this tool 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?

The tool has zero parameters, so the 100% schema coverage is trivially complete. The description adds no parameter-specific information, but none is needed. Per the rubric, 0 params warrants a baseline of 4.

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 ('Read') and a specific resource ('public SqueezeOS x402 discovery contract'), and clarifies that it 'reports payment terms.' This clearly distinguishes it from sibling tools like x402_evidence or x402_readiness by naming the contract as the object of inspection.

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 indicates when to use it: to read the SqueezeOS x402 discovery contract and obtain payment terms. It also states what it never does ('never signs, submits, or settles a payment'), effectively telling an agent when not to use it. However, it does not explicitly name alternative tools or conditions for choosing them.

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