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

Annotations already declare readOnlyHint=true and openWorldHint=true, and the description adds meaningful behavioral context: it performs DNS queries only and does not connect to the domain itself. It also discloses that SPF and DMARC presence/policies are reported. Rate limits, auth needs, and exact response structure remain unspecified.

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 tightly written sentences with zero waste. The core purpose and record types are front-loaded, followed by the important no-connection constraint.

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 two-parameter, read-only lookup tool with no output schema, the description covers what is resolved and what extra findings (SPF/DMARC) are reported. It does not describe the response shape in detail, but given the annotations and low complexity, it is nearly 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?

Schema description coverage is 100%, so the schema already fully documents both the domain pattern and the record-type enum values. The description lists the same record types but adds no syntax, format, or default behavior beyond what the schema provides, making the baseline 3 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?

States a specific verb ('Resolve'), resource ('public DNS records'), and scope (the exact record types plus SPF/DMARC reporting). It is clearly distinguishable from siblings like domain_rdap, which handles registration data rather than DNS records.

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 usage for passive DNS inspection and notes that no connection is made to the domain, which hints at safe read-only use. However, it never explicitly says when to use this tool versus alternatives such as domain_rdap or url_to_markdown, leaving routing to inference.

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