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

No annotations are provided, so the description carries the full burden. It does not disclose whether the lookup is recursive, which record types (A, AAAA, MX, TXT, etc.) are returned, whether it hits a live nameserver or cache, or any rate limits. A read-only network call is implied but never stated.

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 efficient sentence with the key information front-loaded. Appropriately sized for a one-parameter tool, though it is thin on substance.

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 network lookup tool with no annotations and no output schema, the agent needs to know what record types come back, whether errors are possible (NXDOMAIN, timeouts), and what the response shape is. None of that is covered.

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 100% (the domain field documents its own format with an example), so the baseline is 3. The description adds no syntax or format details beyond what the schema already provides.

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?

Clear verb (look up) plus resource (DNS records) and scope (any domain). It doesn't differentiate from siblings like check_ssl_certificate or get_forecast, which also touch network/domain lookups, but the purpose itself is unambiguous.

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?

No when-to-use guidance, no mention of which record types are retrievable, and no routing to alternatives. The agent must infer everything from the name and schema.

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