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

Annotations say readOnlyHint=false and destructiveHint=false, so the agent knows it mutates state harmlessly. The description adds real context beyond that: the tool requires an authenticated Proof account and describes the auth flow (/mcp Authenticate or start_login). It doesn't say whether the check is synchronous or requires polling, which is a gap.

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 behavioral instruction is front-loaded and short; the auth paragraph is longer but earns its place by explaining a non-obvious prerequisite. Slightly verbose in the parenthetical CLI detail, but not wasteful.

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?

With no output schema, the description should clarify what a check returns (pass/fail, or a result requiring a separate status call to get_user_domain_verification_status). It covers auth and timing but leaves the outcome/polling model unstated.

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% for the single session_id parameter, so the schema already carries the semantics. The description adds nothing about the session_id's origin or format, so baseline 3 applies.

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 names a specific verb ('Trigger a check') and resource ('domain verification challenge'), which distinguishes it from read-only siblings like get_user_domain_verification_status. It stops short of explicitly naming which sibling to prefer, but the action is unambiguous.

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 clear timing context: 'Call after placing DNS record or HTTP file.' It also states the precondition that a Proof account is required. It does not name alternative tools (e.g. get_user_domain_verification_status for polling results), so it falls short of full when/when-not guidance.

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