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

The description goes well beyond the annotations by disclosing the return state machine (state, step/of, done, waiting, reason, retry_after_s, seen, next, can_do, say), the polling cadence, and the fact that read-only workspace members may call it. It also clarifies the immediate-advance behaviour, which is what makes readOnlyHint=false make sense rather than look inconsistent.

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?

Purpose and the immediate-advance nuance are front-loaded in the first clause, and the usage paragraph is tight. The parenthetical enumeration of every returned field is long but justified given there is no output schema, so it is dense rather than 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 carries the return-value burden and does so by enumerating the fields and their meaning, then adds the polling/branching protocol and the permission note. Nothing an agent needs to call and interpret this 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 description coverage is 100% and both parameters (hostname, domain_id) are already documented with their 'pass this or...' relationship in the schema. The description adds no syntax, format, or precedence detail beyond that, so the 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?

States a specific verb (check progress) and resource (custom domain), and adds the non-obvious second capability — advancing the state one step immediately rather than waiting for the background pass. An agent can distinguish this from list_domains, bind_domain, or set_domain_route without opening a schema.

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?

Explicit when-to-use rules are given: poll after retry_after_s until state=active, branch on next=user_action vs next=contact_us, and call it when the user asks 'is it ready' or 'why does it not open'. Alternative behaviours are named, not left to inference.

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