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

Adds substantial context beyond the annotations: '(needs account token)' flags an auth prerequisite, 'Does not charge' rules out billing, and the 301-redirect and re-check semantics explain what actually happens on repeat or multi-domain sites. This is exactly the kind of detail openWorldHint/destructiveHint cannot convey.

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?

Five short, front-loaded sentences with no filler; the auth note is prefixed so it is seen first, and each sentence carries a distinct fact (scope, non-transfer, response contents, redirect behavior, idempotency, cost).

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 compensates by describing the return payload (A record and TXT ownership record), and it covers cost, auth, idempotency, and multi-domain behavior. Nothing an agent needs before calling 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%, so both parameters are already documented with examples in the schema. The description implies the site/domain relationship but adds no format or constraint detail beyond the schema, 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 and resource ('Attaches a domain registered at another registrar to a site') and immediately scopes it by negation ('Nothing is transferred or bought'), which separates it from transfer_domain_out, point_domain, and search_domain without the agent needing to open another 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?

Gives clear triggering context (domain held at another registrar) plus two edge-case behaviors: on a site that already has a domain the name becomes a 301 redirect, and a repeat call re-checks ownership rather than duplicating. It never names a sibling alternative by name, so routing is inferred rather than explicit.

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