InstaDomain

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

With no annotations provided, the description carries the full burden. It discloses critical behaviors: creates a Stripe checkout session, returns a URL for browser completion, transfers legal ownership to the registrant, and enables WHOIS privacy by default. Minor gap: does not mention error handling, cancellation behavior, or idempotency for payment sessions.

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?

Well-structured with the critical prerequisite warning front-loaded under 'IMPORTANT.' Information is organized logically into flow explanation, Args, and Returns sections. Slightly verbose but justified given the financial/safety criticality and complexity of 11 parameters. No redundant sentences.

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 this is an 11-parameter financial transaction tool with no annotations, the description is remarkably complete. It covers prerequisites, parameter semantics (compensating for empty schema), privacy implications (WHOIS), ownership transfer, return values (order_id, checkout_url), and payment security context. Sufficient for safe agent operation.

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 input schema has 0% description coverage, but the description fully compensates with a comprehensive Args section. It provides format specifications for critical fields: country requires '2-letter ISO country code,' phone requires '+1.5551234567' format, domain includes an example, and org_name notes it is optional for individuals. This ensures correct invocation despite the bare schema.

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 'Start[s] the purchase flow for an available domain via Stripe checkout,' providing a specific verb, resource, and mechanism. It implicitly distinguishes from sibling buy_domain_crypto by specifying Stripe, and explicitly differentiates from check_domain by noting the prerequisite relationship.

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?

Exceptional guidance provided: explicitly mandates calling check_domain first to get pricing, requires showing the user the price and obtaining explicit confirmation, and warns 'Never call buy_domain without the user seeing and approving the price first.' Clear sequencing and safety guardrails are established.

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