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

Beyond the annotations, the description reveals a 90-day verification expiry, live re-checking on later calls, the human-at-DNS-host prerequisite, and the refusal categories for non-domain values. This materially predicts side effects and time-dependent behavior rather than just saying 'verify.' No contradiction with readOnlyHint=false/idempotentHint=true/destructiveHint=false.

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 dense but well structured, with action: prefixes and a front-loaded purpose. It could be slightly more scannable with bullets, but every sentence contributes to the workflow, constraints, or downstream events.

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?

It covers all four actions, the DNS TXT record format, the human step, verification duration, downstream tools, watch events, and refusal cases, which is strong for a complex multi-action tool with no output schema. Missing explicit error handling for failed checks and per-action return shapes, but those are minor against this level of detail.

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 parameters are already documented; the description adds workflow-level meaning by mapping each action enum value to its effect (start returns a record to add, check confirms live DNS, watch toggles lanes, status lists state). It does not add much to lanes/active beyond what the schema states, but the action state machine is valuable.

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 the core purpose—prove control of a domain, then watch it—and enumerates the four actions (start/check/watch/status) with one-line meanings. It also draws a hard boundary that only domains are accepted, never email addresses, people, or private/internal names, which makes the scope unmistakable.

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 gives a clear workflow: start gets the DNS TXT record, a human adds it, check confirms, then watch subscribes to daily estate.cert/posture/breach events. It also lists exclusions ('Domains only... all three are refused'), but it does not explicitly name an alternative sibling to choose instead when this tool is not appropriate.

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