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

Annotations already establish readOnly, idempotent, openWorld, non-destructive, so the safety profile is covered. The description adds genuine behavioral value beyond that: it discloses the output contents (each referral and glue, lame or unreachable servers, final answer, verdict), which compensates for the absent output schema.

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 dense sentence that front-loads the usage trigger before the behavior and return details. Nothing is redundant, though the return-value list is packed in tightly rather than broken out.

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 usefully enumerates what a trace returns and gives the invocation trigger. It omits operational expectations (traces are slow/network-bound) and the meaning of the verdict, leaving minor gaps for a complex multi-hop diagnostic.

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%, so both parameters (name, type) are already documented in the schema, including the "domain"/URL-host aliasing and the type default. The description adds no further parameter meaning, so 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?

States a specific verb and resource (walk the delegation for a name) with explicit scope (root to authoritative) and anchors it to a well-known command (dig +trace). The analogy cleanly distinguishes it from the sibling `dig` (single query) and `dnssec_chain` (validation chain).

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 the person wants to walk the delegation for a name" gives a clear triggering condition. It does not, however, name alternatives or exclusion cases (e.g. when to prefer plain `dig`, `check_domain`, or `dnssec_chain` instead), so the routing guidance stops short of 5.

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