Find domains and domain hacks with live availability, registrar prices, and keyword search demand.
Scored across 3 tools
check_availability and search_domain both check availability for specific domains, with check_availability supporting batches and search_domain adding quotes and TLD expansion. An agent could easily select the wrong one despite the descriptions. find_domains is distinct, but the boundary between checking and searching a specific name remains blurry.
All tool names follow a consistent verb_noun pattern with lowercase underscores: check_availability, find_domains, search_domain. Minor singular/plural variation does not hurt predictability.
Three tools is a well-scoped set for a domain discovery and lookup server. Each tool covers a distinct intended workflow: brainstorming, batch availability checks, and price quote searches.
The server covers the core domain domain: ideation, availability checks, registration pricing, renewal details, and registrar links for final purchase. No major lifecycle gap is evident for a lookup-focused tool set.
Check availability for a specific list of full domains (e.g. ['acme.com','acme.ai']). Returns availability, renewal details where supplied, and a registrar link. This fast lookup does not supply a registration quote; use search_domain for prices. Up to 25 domains per call.
| Name | Required | Description | Default |
|---|---|---|---|
| domains | Yes | Full domain names to check, each including its extension (e.g. ['getacme.com','acme.ai']). Up to 25 at a time. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare readOnlyHint and openWorldHint, but the description adds useful behavior: it is a 'fast lookup', returns availability/renewal details/registrar link, and caps the input at 25 domains. This goes beyond what the annotations provide without contradicting them.
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 tight sentences front-load the core purpose, then cover return contents, the pricing limitation, the sibling alternative, and the call limit. There is no filler or redundant 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?
This is a simple single-parameter tool with a fully documented schema and no output schema. The description covers return values, constraints, and the key sibling routing, while annotations cover safety and open-world assumptions. Nothing significant is missing.
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%: the domains parameter is already fully documented with the format, examples, and the 25-domain limit. The tool description essentially restates this information rather than adding new parameter-level meaning.
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 the specific action 'check availability' against a specific resource: a list of full domains, with a concrete example. It also distinguishes itself from search_domain by noting that it does not provide registration quotes, so an agent can tell the tools apart.
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?
Explicitly says this is a fast lookup that does not supply registration quotes and directs the agent to search_domain for prices. It also implies via 'specific list' that this is for known domains, not discovery, though find_domains is not explicitly named as the discovery alternative.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Brainstorm domain names for an idea, product, or company. Returns brandable names and any domain hacks supplied by the source, with availability and monthly keyword search-volume where available. Cached ideas receive a new availability check. Unknown availability and missing registration quotes are null, never reused from an old search. Use search_domain for a fresh quote or follow the registrar link.
| Name | Required | Description | Default |
|---|---|---|---|
| idea | Yes | The company name, product, or idea to generate domain names for. Example: 'an AI tool that writes SQL'. | |
| tlds | No | Optional. Restrict results to these TLD extensions without the dot (e.g. ['com','ai','io']). Omit to let the finder pick the best-fitting extensions, including domain hacks. | |
| purpose | No | Optional. What the domain is for (e.g. 'startup', 'blog', 'portfolio', 'saas'), to steer the style. | |
| description | No | Optional. A longer description of the business, for more relevant names and better-fitting extensions. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate readOnlyHint and openWorldHint, and the description adds meaningful behavior beyond those: cached ideas receive a new availability check, and unknown availability/registration quotes are null and never reused from an old search. This gives the agent an accurate model of data freshness and result reliability. No contradiction with annotations exists.
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 description is five sentences long, dense but largely purposeful: main function, result contents, freshness behavior, null handling, and an alternative tool reference. Every sentence contributes, though phrases like 'any domain hacks supplied by the source' are slightly awkward and the sentence about cached ideas could be tightened. It is efficient without being minimal.
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 output schema, the description does a good job explaining what callers get back: brandable names, domain hacks, availability, monthly keyword search-volume where available, and registration quotes with null fallback. It also explains data freshness and where to go for a fresh quote. It still leaves some details unstated, such as exact response shape, ordering, or limits, but these are less critical for a brainstorming 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?
The input schema has 100% description coverage, so the baseline is 3 and the schema already documents idea, tlds, purpose, and description. The description adds only a light tie between the idea parameter and 'an idea, product, or company' and does not materially deepen understanding of the other parameters. It does not need to compensate for a schema gap because none exists.
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 opens with a specific verb and resource: 'Brainstorm domain names for an idea, product, or company.' It clearly distinguishes the tool from siblings by emphasizing both generation of brandable names/domain hacks and availability data, and it explicitly points to search_domain for a fresh quote. The purpose is unambiguous and differentiates from check_availability and search_domain.
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 provides clear usage context: it is for brainstorming domain names rather than getting a final quote. It explicitly says 'Use search_domain for a fresh quote or follow the registrar link,' which routes the agent away from this tool for that need. However, it never mentions the check_availability sibling or says when to use that instead of this tool, so the alternative guidance is incomplete.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Request availability and current quotes for a specific name across supported TLD extensions at once. Give a bare label ('acme') to see acme.com, acme.io, acme.ai... or a full domain ('acme.io') to check that one. Availability, registration prices, and renewal details are returned when supplied, alongside a registrar link. Missing fields stay unconfirmed; confirm final terms at the registrar.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | The name to check. A bare label ('acme') is expanded across many TLDs; a full domain ('acme.io') checks that exact domain. | |
| tlds | No | Optional. Limit to these TLD extensions without the dot (e.g. ['com','co','io']). | |
| exact_extension | No | Optional. If the name already includes an extension, set true to check only that exact domain instead of expanding across TLDs. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, and the description adds useful behavioral context: that availability, prices, and renewal details are returned when supplied, and that missing fields stay unconfirmed with a recommendation to verify at the registrar. This goes beyond the annotations and helps set expectations about data reliability.
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 description is three concise sentences that front-load the core purpose and provide examples and caveats without unnecessary fluff. It is well-structured and efficient.
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?
Given the tool's moderate complexity, the schema's full coverage, and annotations, the description is largely complete. It explains the returned data, the unconfirmed fields, and the two input modes. It does not explicitly mention the tlds filter, but that is adequately described in the schema.
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% with descriptive parameter texts, and the description adds valuable examples and clarifies the expansion behavior for bare labels and the exact_extension use case. It enhances understanding of the 'name' parameter beyond the schema alone.
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 tool's purpose: to request availability and quotes for a name across multiple TLDs at once, with examples for both bare labels and full domains. It distinguishes itself from likely siblings by emphasizing the multi-extension capability, though it doesn't explicitly name the alternatives.
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?
It explains when to use the tool (checking a name across many extensions) and even covers the two input modes (bare label vs full domain) with concrete examples. However, it doesn't mention when NOT to use it or compare it to sibling tools like check_availability or find_domains.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
check_availabilityfind_domainssearch_domainLive domain availability and prices across registrars, ranked by true two-year cost.
Compare domain registration and renewal prices across registrars and check exact-name availability.
Search newly registered, expired, aged, active, deleted and for-sale domains, plus WHOIS and DNS.
Compare domain prices across 145+ registrars and 1,100+ TLDs, find promo codes, check availability.
Add one secure layer between your agents and this server.
