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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds an explicit authentication requirement and scopes the operation to externally managed DNS setups, which is useful context beyond the structured annotations. No contradictions.

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 a single sentence that front-loads the purpose, records types, and use context. It starts with a redundant repetition of the tool name, but this is minor and does not detract from readability.

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 simple read-only lookup, the description covers what records are returned, the qualifying scenario (external DNS), and authentication. No output schema exists, but the sentence adequately indicates return content. It does not discuss output format, which is a minor gap.

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 coverage is 100%, so the schema already explains both parameters fully. The description adds no additional parameter-level meaning; it only restates that these are DNS records needed by a mail domain.

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 ('Get') and a precise resource ('DNS records a mail domain needs'), enumerating record types (MX, SPF, DKIM). The 'managing DNS externally' clause also frames why this tool exists, distinguishing it from general DNS-listing tools without naming one.

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 tells the agent when this tool applies: when customers manage DNS externally and need the required DNS records. It does not explicitly name alternatives like verifyMailDns or listDnsRecords, but the external-DNS context is a clear usage signal.

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