add_custom_domainRegister a registrable domain (e.g. example.com) the user owns and detect its DNS provider. Returns the provider and whether one-click connect is available. Then attach sites with add_subdomain.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | registrable domain you own, e.g. example.com |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Input schema / properties / domain / descriptionAdded value: +"registrable domain you own, e.g. example.com"Output schema / (root)Previous value: -nullNew value: +{
+ "$schema": "http://json-schema.org/draft-07/schema#",
+ "additionalProperties": false,
+ "properties": {
+ "result": {}
+ },
+ "required": [
+ "result"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds context beyond annotations: 'detect its DNS provider', 'one-click connect', and guidance to use add_subdomain next. Annotations indicate idempotent and open world, which are consistent with registration behavior.
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 sentences, front-loaded with action and returns, no unnecessary words. Efficient and clear.
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 single-parameter tool with output schema and rich annotations, the description fully covers what the tool does, what it returns, and the next step. No gaps.
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 baseline 3 is appropriate. The description repeats schema info ('registrable domain you own') but doesn't add significant new semantics.
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 clearly states the verb 'Register', the resource 'custom domain', and specifies it detects DNS provider and returns provider/one-click connect availability. It distinguishes from siblings like add_subdomain by noting the subsequent step.
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 description implies when to use (registering a user-owned domain) and mentions the next step (add_subdomain). It provides context but doesn't explicitly state when not to use or list alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.