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

Annotations already declare read-only, idempotent, non-destructive, and open-world behavior. The description adds substantial operational context beyond that: it returns the exact paid x402 request, costs $0.05 per call, includes the response schema and an example, requires posting the returned JSON body with an x402 or MPP client, and refuses bad input before any charge. This is rich behavioral disclosure with no contradiction.

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 front-loaded with the usage condition and alternative, then follows with the mechanics of payment and retrieval. It is appropriately sized for a paid batch tool with no output schema, though slightly dense; each sentence earns its place.

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 fills the gap by explaining that the response is the exact paid x402 request including schema and example, and that the caller must POST it to the given URL with an x402 or MPP client. Combined with annotations and full schema coverage, an agent has everything needed to call it 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?

Schema description coverage is 100%, so the single parameter is fully documented in the schema itself. The description reinforces the batch limit ('up to 10 domains in one POST') and the close relationship to /domain/report, but does not add syntax or format detail beyond the schema baseline.

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 states a specific verb and resource (batch domain reports), scopes it to up to 10 domains in one POST, and explicitly distinguishes it from the single-domain sibling via 'For one domain use domain_report.' An agent can tell exactly what this tool does and when to choose it over domain_report.

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?

It gives explicit when-to-use guidance ('when you must vet several domains at once') and an explicit alternative ('For one domain use domain_report'), plus the hard limit of 10 domains. No inference is needed to route between this and the single-domain sibling.

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