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

With no annotations, the description discloses key behaviors: credit pack requirement, zero cost for pack holders, and domain limit. It does not detail error handling or what happens without a pack, but covers main constraints.

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?

Extremely concise: three short sentences. The action and key constraints are front-loaded. No redundant 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 simple check tool with one parameter, the description covers preconditions and constraints but lacks information about the return value (e.g., boolean or list of results). Since no output schema exists, the description should hint at what the agent receives.

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%, providing baseline 3. The description adds value by specifying 'Max 20 domains', a constraint not in the schema. No further parameter details are needed as the schema adequately describes the 'domains' parameter.

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 description uses the verb 'check' and resource 'domain availability', clearly indicating the tool's purpose. It distinguishes from sibling tools 'get_credits_balance' and 'search_names' by focusing on availability checking, but does not explicitly differentiate from 'search_names' which might overlap.

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?

Provides clear context: requires a Starter or Pro credit pack, no credit cost for pack holders, and a maximum of 20 domains. However, it does not specify when not to use this tool or suggest alternatives.

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