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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so the safety profile is covered. The description adds value beyond that by disclosing the transport (Cloudflare DNS-over-HTTPS, an external dependency) and the return contents (record data plus TTLs). It does not mention failure behavior for NXDOMAIN or any rate/abuse limits on the DoH endpoint.

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?

A single well-formed sentence with zero filler, front-loaded with the action and resource and ending with the return payload. Nothing is padded.

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 simple read-only lookup with safety fully covered by annotations and no output schema, the description tells the agent enough to call it: what it resolves, the allowed record types, and roughly what comes back. Remaining gaps (hostname format, error/empty-result behavior) are minor but real.

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%, so the description must carry the burden, and it largely does not. It re-lists the record types already enumerated in the schema and names 'hostname' without clarifying format (bare host, no scheme/URL, no trailing dot) or the A default.

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?

States a specific verb (Resolve), the resource (DNS records), the enumerated record types, the upstream resolver (Cloudflare DNS-over-HTTPS), and what comes back (record data and TTLs). This is unmistakably distinct from siblings like check_ssl, check_cors, or trace_redirects.

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?

Usage is implied — you call it to look up DNS records for a hostname — but there is no explicit when-to-use, no statement about prerequisites, and no routing to alternatives among the sibling checkers. The default of type A is left entirely to the schema.

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