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

Annotations already declare idempotentHint=true, destructiveHint=false, readOnlyHint=false. The description adds genuinely new context: an account token is required, no money moves, and the domain must already be on the account. It does not explain what 'rearranging' changes on the target site, but the added auth and no-cost disclosures go beyond the annotations.

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 front-loaded first sentence is efficient, but three of the remaining sentences repeat the same anti-purchase instruction in slightly different words ('never buy anything without asking', 'never buy a domain, email or subscription without asking', 'when something costs money, give me the payment link'). That redundancy consumes roughly half the description without adding tool-specific information.

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 two-parameter idempotent mutation tool with no output schema, the description covers the auth prerequisite, the mutation scope, and the cost boundary. What is left implicit is the resulting state change on the target site, a minor gap given the annotations already signal safety and idempotency.

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 both parameters (domain, to_site_id) are already self-documented in the schema. The description restates that the domain must already be on the account, which duplicates the schema description rather than adding syntax or format detail. 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 first sentence states a specific verb+resource: rearranging/pointing a domain that is already on the account, which distinguishes it from search_domain (find) and get_checkout_link (purchase). The negative scoping ('does not buy a name', 'does not edit DNS at someone else's registrar') sharpens the boundary further. It stops short of the crispness of naming a specific sibling.

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 strong when-not guidance: this is not a purchase tool and not a third-party registrar DNS editor, so an agent knows not to route buying or external DNS tasks here. However, it never names the correct alternative sibling (search_domain, get_checkout_link) for those excluded cases, 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.