domain_fetch_reverse_ip

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

The tool already has annotations (readOnlyHint, idempotentHint) and the description adds details beyond annotations: IPv6 limitation, daily quota, caching, and API source. No contradictions found.

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 and each sentence adds value. Slightly verbose but effective. Could be tightened slightly without losing clarity.

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 (one parameter, no nested objects) and presence of output schema, the description covers all necessary context including limitations, caching, and error handling.

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 single parameter is fully documented in schema (100% coverage). The description adds context about domain resolution to IPv4, which is not in 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 clearly states the tool performs reverse IP lookup to find co-hosted domains. It explicitly mentions the input type and use cases, distinguishing it from sibling tools like 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?

The description explains when to use the tool and what input to provide. It mentions daily quota and fallback feedback mechanism. However, it does not explicitly list alternatives or when not to use it.

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