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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is given. The description still adds genuinely new context: nothing is applied to DNS, a human publishes, approval must be obtained, record strings must be printed verbatim, and guidance.note must be relayed as given for edge cases. That is real added value beyond the annotations, though it stops short of describing response shape or failure conditions in depth.

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?

Front-loaded with the read scope before the operational constraints. Every sentence carries a distinct rule (routing to check_domain_verification, verbatim printing, human approval, note relay) with no restatement of the name or title.

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?

Output schema exists, so return values need not be explained, and the description still flags the guidance.note field. For a one-parameter read tool with full annotation coverage, nothing an agent needs in order to call it correctly is missing.

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% and the single domain parameter is documented in detail, including the not-found / ownership-non-disclosure behavior. The description adds no parameter-level syntax or format beyond what the schema already provides, so baseline 3 is correct.

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 (read) and precise resource (the records a monitored domain still needs), then enumerates the two record classes: the ownership check pre-verification and the DMARC reporting record post-verification plus its observed publication state. This clearly differentiates it from siblings like check_domain_verification, which it explicitly says issues the record rather than reading it.

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?

Gives an explicit routing rule: if a verified domain returns with no reporting record, call check_domain_verification once because that tool issues it. It also sets the boundary against DNS-writing tools of the agent's own, requiring human approval and showing records first.

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