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

Annotations already declare read-only/idempotent/non-destructive, but the description adds substantial extra context: ~5-15s runtime, $2 USDC x402 payment passed in _meta['x402/payment'], and that failures or invalid input are not charged. These are operationally decisive facts the annotations cannot convey.

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?

Dense but front-loaded: purpose first, then coverage, then return shape, then cost/failure semantics. The long parenthetical check list is justified by the tool's breadth, though it could be trimmed slightly.

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?

With no output schema, the description carries the return contract itself: A-F grade and score, action plan sorted by severity with fix and effort, and raw sections. Combined with cost and failure behavior, an agent has everything needed to call and interpret this 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 description coverage is 100% and there is a single required parameter, so the schema already documents format and examples. The description adds only the implicit 'one domain' scope constraint, so the baseline 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?

States a specific verb+resource ('full site audit report for one domain') and enumerates the checks it performs, so the agent knows the scope precisely. It explicitly differentiates itself from the sibling domain_grade ('Use domain_grade for just the letter').

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?

Gives concrete use cases (client reports, vendor reviews, pre-launch check), names the narrower alternative and when to prefer it, and states failure/charging conditions. The when-to-use decision is fully resolved without opening a schema.

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