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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new context: it works with no account, prices are in EUR, and buying is a human dashboard step that this tool never performs. The repeated 'never buy without asking' sentences add emphasis but little new information.

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 purpose and pricing behavior are well front-loaded. However, the final three sentences ('Never buy anything... Never buy a domain, email or subscription... give me the payment link') are substantially redundant with each other, diluting an otherwise efficient definition.

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?

There is no output schema, and the description compensates by stating what comes back (availability and price per TLD, in EUR) and that no account is needed. This is sufficient for a single-parameter read tool, though it could say more about result shape for multi-TLD lookups.

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 the single parameter is fully documented in the schema, so the baseline is 3. The description restates the same full-name vs bare-name behavior rather than adding format or constraint detail beyond the schema.

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: check domain availability and price. It clearly separates this lookup action from siblings like point_domain and get_checkout_link, which perform different tasks. An agent can identify the intent without opening the 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 concrete input-format guidance: a full name is one lookup, a bare name is checked across .com/.nl/.app, and it frames the use case ('use it to propose a REAL free name'). It also clarifies that buying is a separate human step. No sibling tool is explicitly named as an alternative, so it falls short of a 5.

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