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

With no annotations, the description carries behavioral weight well: it discloses the payment method (USDC), the effect on the registration (+1 year), an external prerequisite (unlock at current registrar), and that completion is asynchronous over ~5-7 days. It omits what happens on failure (refund/charge timing) and whether funds are pulled immediately.

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?

Three compact sentences, all front-loaded: what it does, how it's paid, prerequisite, then duration. No filler and nothing an agent must scan past.

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?

Covers the essentials for a paid, slow mutation (cost currency, prerequisite, duration) but a tool with 8 parameters, 25% schema coverage, no annotations and no output schema needs more — particularly payment-source semantics (pay_with vs. token/chain) and what the call returns (order id, status to poll via check_order).

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 only 25% (chain and token are described; domain, auth_code, years, pay_with, ref, idempotency_key are not). The description clarifies auth_code as the EPP code and token default as USDC, but leaves years, pay_with (crypto vs balance), ref, and idempotency_key unexplained, and 'adds 1 year' leaves the relationship to the `years` parameter ambiguous.

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 ('transfer a domain in from another registrar') plus the mechanism (auth/EPP code) and payment currency, which cleanly separates it from renew_domain, create_order, and buy_with_balance. An agent can tell immediately this is an inbound registrar transfer.

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 an explicit prerequisite ('Unlock it at the current registrar first') and a timing expectation (~5-7 days), which is real usage guidance. It stops short of naming when to prefer this over siblings like create_order/pay_order or what to do if the transfer fails.

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