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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so safety is covered. The description adds genuine value beyond that by enumerating how the chain terminates: addresses, none, resolver failure, NXDOMAIN (dangling), a loop, or an inside name, which tells the agent what to expect from a traversal.

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, zero filler, with the usage condition front-loaded and the return semantics following immediately. Every clause earns its place.

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?

With no output schema, the description carries the burden of describing results and does so via the termination taxonomy. It omits depth limits, resolver choice, and timeout handling, but for a single-parameter read-only tracer it is close to complete.

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?

There is a single parameter with 100% schema description coverage, and the schema itself documents the domain alias and URL-as-host behavior. The description adds no further syntax or format detail beyond the schema, so the baseline 3 applies.

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 states a specific verb and resource: follow a name that is a CNAME and return each hop with target and TTL. It implicitly distinguishes itself from siblings like dig or check_domain by framing the task as chain-following, so an agent can select it without opening the schema.

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?

"Use when a name is a CNAME and the person asks where it leads" gives a clear triggering condition. It stops short of naming when-not-to-use cases or explicit alternatives (e.g., use dig for a single lookup instead), so it falls one step below full routing guidance.

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