domain_fetch_domain_rdap

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true. Description adds context: 'Read-only. No side effects. Idempotent.' Also describes return fields and 4-hour cache. No contradictions.

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?

Efficiently front-loaded with main action and key details. Every sentence adds value: usage guideline, parameter hint, alternative tools, source, cache, feedback mechanism. No fluff.

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 simple tool with 1 param, full schema coverage, good annotations, and existing output schema, the description is fully complete: it explains purpose, usage, return content, caching, and provides fallback feedback mechanism.

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 100% with a clear description. Description adds a concrete example ('example.com not https://example.com') and clarifies required format, providing additional value beyond 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?

Clearly states 'Fetch domain registration details via IANA RDAP' with specific verb and resource. Distinguishes from sibling tools like domain_fetch_ssl_certificate_chain and domain_fetch_dns_records by specifying different use cases.

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?

Explicitly says when to use ('when you need registration metadata') and when not to use with named alternatives. Also includes caching info and a feedback instruction for gaps.

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