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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description goes beyond them by disclosing the return shape (id, title, url) despite no output schema, and by defining the id→fetch handoff. It doesn't mention whether DNSai requires an API key (request_api_key is a sibling) or how many results come back.

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?

Two sentences, both front-loaded with the essential information — what is searched and what comes back — with no filler or restatement of the name.

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?

For a one-parameter, no-output-schema tool, the description supplies the otherwise-missing return shape and the follow-up path, which is what an agent needs to chain calls correctly. Auth requirements and result volume remain unstated.

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% and the single query parameter is fully documented there, including that it accepts natural language or a bare domain. The description only echoes the domain case and slightly narrows the schema's stated flexibility, so it adds marginal 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?

The definition gives a specific verb+resource ("Search DNSai for a domain") and immediately enumerates the content covered — DNS records, email-security posture, DMARC, WHOIS — which positions it as the aggregate entry point among the granular siblings (dns_lookup, dmarc_check, whois_lookup). It stops short of explicitly contrasting itself with those siblings, but the scope statement does most of that work.

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 two-step workflow is made explicit: search by domain to get result items, then "pass a result id to fetch for the full data." That is real routing guidance toward the fetch sibling. What's absent is when to prefer the focused tools (dkim_discover, spf_analyze) over this broader search.

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