InstaDomain

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

With no annotations provided, the description carries the full disclosure burden. It successfully adds behavioral context: uses 'fast RDAP lookups,' lacks pricing data, and returns a specific structure (summary counts plus per-domain details). Since an output schema exists, this level of summary is appropriate.

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 tightly structured across four sentences: purpose/scope, technical method, return format, and parameter definition. Every sentence adds unique value with no redundancy or filler.

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 low complexity (single array parameter) and the presence of an output schema, the description is complete. It covers the operational method (RDAP), limitations (no pricing, max 50), and return structure without needing to replicate full output schema details.

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 0%, requiring the description to compensate. It does so effectively by documenting the 'domains' parameter as a 'List of domain names to check (max 50),' adding the critical cardinality constraint missing from the 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 explicitly states the tool checks availability of 'up to 50 domain names in one call,' using specific verbs (Check) and quantifying the bulk scope. This clearly distinguishes it from the singular sibling tool 'check_domain' by emphasizing the batch capability.

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?

The description implies bulk usage through the 'up to 50' constraint and explicitly notes 'no pricing' (indicating when not to use for cost inquiries). However, it stops short of explicitly naming 'check_domain' as the alternative for single-domain checks.

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