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

There is a direct contradiction: the description says the tool 'activates the domain for email when all records are found,' which is a state-changing side effect, while annotations declare readOnlyHint: true. This makes the behavioral disclosure misleading despite also revealing that it returns missing records and requires authentication.

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 compact and front-loaded with the main purpose. It wastes no words except for repeating the tool name 'verifyMailDns:' at the start, which is minor and does not materially hurt clarity.

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?

The description includes important context: it activates the domain, returns missing records, and requires authentication. However, it does not specify which DNS records are checked or how this relates to sibling tools like enableMailDomain and getMailDnsRecords, leaving some practical gaps.

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%; both 'domain' and 'sessionKey' are already documented clearly in the schema. The description adds no additional parameter-level meaning, so the baseline score of 3 is appropriate.

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: 'Check that a mail domain's DNS records resolve.' It also clearly distinguishes itself from sibling tools like getMailDnsRecords and enableMailDomain by combining verification with activation, so an agent knows what this tool uniquely does.

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 implies when to use this tool: when you need to verify DNS records and activate the domain once records are found. However, it does not explicitly name alternatives or state when not to use it, leaving the routing decision somewhat to inference.

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