Register a new domain (PAID)

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

Adds significant context beyond the annotations (destructiveHint=true, readOnlyHint=false) by disclosing that the action 'SPENDS MONEY from the Namecheap account balance and is not reversible,' describes the dry-run behavior, and explains that the registrant contact applies to all roles unless overridden. It also warns about ccTLD extended attributes, all of which are critical operational details.

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 appropriately sized for a complex, high-risk operation. Each sentence earns its place: the money warning is front-loaded, the confirm flag behavior is critical, contact roles and ccTLD extras are necessary, and the pointer to related tools prevents misuse. 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?

Given the tool's complexity (9 parameters, nested objects, paid irreversible action), the description covers all essential aspects: prerequisites, the confirm gate, contact requirements, special ccTLD handling, and links to sibling tools for availability/balance checks. The output schema exists, so return values need no description. It is fully adequate for an agent to safely invoke 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 coverage is 89%, so the baseline is 3, but the description adds crucial meaning for key parameters: confirm (controls dry-run vs actual charge), contact (applied to all roles unless overridden), and extendedAttributes (raw Namecheap field names). It does not explain nameservers or enablePrivacy, but those are adequately covered by the schema and simpler in nature.

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 opens with 'Register (buy) a new domain,' a specific verb and resource that immediately distinguishes it from siblings like renew_domain and transfer_domain. It clearly states the action is purchasing, which is unique among the listed tools.

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 when-to-use guidance by instructing to 'Check availability/pricing first with check_domain_availability and confirm funds with get_account_balance,' naming the appropriate alternatives for pre-checks. It also specifies that confirm=true is required to actually place the order, otherwise it returns a dry-run, setting expectations for operational use.

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