Check whether a domain is available to register through UmbHost and its registration price. Optional ISO currency (GBP, EUR, USD, AUD); defaults to GBP. Price excludes VAT.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | One domain name to check, e.g. example.co.uk — the name only: no question, URL, path or list. | |
| currency | No |
Changes observed during successful MCP inspections.
Input schema / properties / domain / descriptionAdded value: +"One domain name to check, e.g. example.co.uk — the name only: no question, URL, path or list."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full burden; it does disclose useful traits such as the GBP default, accepted currency codes, and that the price excludes VAT, and 'check' implies a non-mutating lookup. It does not state whether the result reflects a live registry query, any rate limits, or whether the price is per-year, leaving real behavioral gaps for an unannotated tool.
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 short sentences, front-loaded with the core capability and followed by the only two caveats that matter (currency default, VAT exclusion). No filler or restatement of the tool name.
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 annotations and no output schema, the description does well to name what comes back (availability plus price) and its VAT basis. It is still thin on the shape of the answer and on whether the price is a recurring registration term, which matters for a pricing-adjacent tool.
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 50%: the domain parameter is fully documented in the schema, while currency has no schema description. The description compensates by enumerating the accepted ISO codes (GBP, EUR, USD, AUD) and the GBP default, which is exactly the missing information, though it doesn't specify behavior for unsupported codes.
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 (check availability) plus the resource (a domain) and the provider, and adds the secondary output (registration price). This clearly separates it from siblings like quote, get_plan, and begin_checkout, which imply pricing or checkout rather than a single-domain availability lookup.
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?
Usage is only implied: an agent can infer this is a pre-registration availability probe, but the description never says when to prefer it over quote or begin_checkout, nor any preconditions. The only explicit guidance is about the optional currency parameter, not about tool selection.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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