domain_fetch_domain_rdap

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

With no annotations provided, the description fully carries the burden. It discloses 'Read-only. No side effects. Idempotent.' and mentions 'Verified source: IANA RDAP. 4-hour cache.' This clearly communicates that the tool is a safe read operation with caching behavior. Missing details on error handling for invalid domains, but sufficient for the tool's simplicity.

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 well-structured: starts with main action, then parameter details, usage alternatives, cache info, and error fallback. It is moderately long but every sentence adds value, with no unnecessary repetition. Could be slightly tighter but remains effective.

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 simplicity (1 required parameter) and the presence of an output schema (so return values need not be described), the description covers all key aspects: purpose, parameter, usage guidelines, behavioral traits, source verification, caching, and a fallback mechanism. It is fully sufficient for an AI agent to correctly select and invoke the 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?

The input schema has 0% description coverage for the single parameter 'domain'. The description compensates by explaining the format ('Domain name without protocol e.g. example.com not https://example.com') and marking it as required. This adds meaningful guidance beyond 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 verb 'Fetch', the resource 'domain registration details', and the method 'via IANA RDAP'. It distinguishes from sibling tools by specifying when to use this tool versus alternatives like domain_fetch_ssl_certificate_chain and domain_fetch_dns_records.

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 states when to use this tool ('Use this when you need registration metadata'), when not to use it (alternatives for certificate history and DNS resolution), and provides a fallback instruction to call report_feedback if the response does not serve the user's need.

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