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

Annotations already provide read-only/destructive/idempotent hints. The description adds meaningful behavioral context: cost ('$0.05'), payment requirement ('x402-paid'), and record contents ('binding hash, policy verdict, findings, optional settlement outcome'). It does not contradict annotations.

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 focused sentences. The first front-loads the tool name, cost, and core action. The second adds a clear usage loop and the benefit. No fluff or repetition.

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's complexity (14 params, nested objects) and existing output schema and annotations, the description sufficiently explains the high-level purpose, cost, and usage pattern. It does not detail error cases or parameter construction, but these are covered by the schema and output schema.

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 input parameter details beyond the schema; it focuses on the purpose and output. No compensation needed since the schema fully documents parameters.

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 clearly states the tool's function: 'bind one x402 payment intent or MCP tool call to a canonical HMAC-signed record'. It names specific resources (payment intent, MCP tool call) and the output type (HMAC-signed record). It also distinguishes itself from verification via 'a third party can check at the free verify endpoint'.

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?

Provides explicit usage context: 'Loop it after every payment or tool call to build a tamper-evident audit trail'. This tells the agent when to invoke it. It also implicitly differentiates from the verify endpoint, but does not explicitly state when not to use other tools.

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