dns_lookup

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

The annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The phrase "using the system resolver" adds real value by telling the agent the answer depends on local DNS configuration rather than a remote service. It stops short of disclosing failure modes (NXDOMAIN, timeouts), caching behavior, or address-family handling.

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?

One sentence, front-loaded, with no filler or redundancy. Every phrase carries meaning.

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?

An output schema exists, so return values need not be explained, and the annotations cover safety. However, for a tool with 0% parameter description coverage the description leaves gaps around accepted hostname formats and error conditions that an agent would want before invoking it.

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 has zero schema description coverage, so the description must compensate. Saying "hostname" does imply the host argument is a name rather than an IP literal, but it says nothing about FQDN format, trailing dots, URL input, or port syntax.

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") and resource ("hostname to its addresses"), which is far more informative than the bare name dns_lookup. It is clearly distinct from siblings like check_tcp_port or network_interfaces, though it does not name any sibling explicitly.

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 offers no when-to-use guidance, no prerequisites, and no alternatives (e.g. when to prefer check_tcp_port or a web_fetch). Usage is only inferable from the verb itself.

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