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

Annotations already cover read-only, idempotent, and non-destructive hints. The description adds valuable behavioral details such as the Status codes (NOERROR vs NXDOMAIN), the inclusion of Answer records with TTLs, and the AD flag for DNSSEC, which are not in the annotations. This enriches the agent's understanding of output and behavior.

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?

The description is front-loaded with the core purpose and use cases, followed by a concrete reverse-lookup example. Every sentence earns its place—no repetition, no fluff, and it is compact for the info it delivers.

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 explicitly explains the response structure (Status, Answer with TTLs, AD flag). It also covers all three parameters, including the 'do' option for DNSSEC. The tool is well-specified for an agent to call correctly without missing information.

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%, with each parameter already documented. The description adds an example for PTR (reversed IP) but does not significantly expand on parameter meanings beyond what the schema provides. Baseline 3 applies because the schema already carries the semantics.

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 starts with a specific verb ('Resolve') and resource ('any DNS record') and immediately clarifies the purpose via concrete use cases ('is DNS propagated?', MX/TXT/SPF/DKIM records, CNAME target). It leaves no ambiguity about what the tool does and is well-distinguished from any potential alternatives.

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?

It clearly states when to use the tool with examples and gives specific instruction for reverse lookup (PTR with reversed IP). However, it does not explicitly mention when not to use it or any alternative tools, though none are listed as siblings. The context is strong enough to guide typical usage.

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