check_domain_availabilityCheck whether a domain is available before registering it to avoid failed registrations. Uses a read-only lookup and returns availability status.
Check read-only domain availability. Requires domains:read when using an API key.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | Domain to check, e.g. example.lt or example.com |
Changes observed during successful MCP inspections.
v2.3.16Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is clear. The description adds a valuable operational context: the required API key scope (domains:read), which an agent must know before invoking with an API key. It does not cover return behavior or rate limits, but the added auth need earns credit above the annotation baseline.
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?
Two short sentences: the first front-loads purpose, the second adds the key prerequisite. No filler or redundancy; every sentence earns its place.
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 one-parameter read-only check with rich annotations and no output schema, the description covers purpose and the key auth requirement. It does not explain what the returned availability result looks like, but with no output schema that is not strictly required, and the definition is otherwise complete for correct invocation.
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 the single 'domain' parameter is already documented with an example in the schema. The description adds no additional syntax, format, or constraint details beyond what the schema provides, so baseline 3 is appropriate.
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 states a specific verb (Check) and resource (domain availability) and adds 'read-only' to signal a safe query. It distinguishes itself from sibling mutation and quoting tools by focusing on availability, though it does not explicitly name an alternative or sibling tool.
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?
The only guidance is 'Requires domains:read when using an API key,' which is an authentication prerequisite rather than when to use this tool versus alternatives. No when-to-use context or exclusions are provided, leaving the agent to infer usage from the name alone.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.