Every domain registrar TLDers tracks, with WHOIS-privacy info and number of tracked TLDs.
| Name | Required | Description | Default |
|---|---|---|---|
| api_key | No | Your TLDers API key. Only needed if your client cannot send an Authorization header or use a ?key= URL. |
Changes observed during successful MCP inspections.
Input schema / properties / api_keyAdded value: +{
+ "description": "Your TLDers API key. Only needed if your client cannot send an Authorization header or use a ?key= URL.",
+ "type": "string"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose what the response contains (WHOIS-privacy info, count of tracked TLDs), which implies a read-only enumeration. It says nothing about read-only safety, pagination, rate limits, or whether the api_key is mandatory, which are the gaps that matter for a tool with zero annotation coverage.
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?
A single front-loaded sentence with no filler; the resource is named before the payload details. Minor deduction because the phrase 'TLDers tracks' is slightly jargon-y where 'the API tracks' would read faster.
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 no-parameter list tool with no output schema and no annotations, the description covers the return fields, which is most of what an agent needs. It omits any note on auth or result size, which would be expected given the absence of annotations and output 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 description coverage is 100% for the single optional api_key parameter, so the schema already explains its purpose and the header/key fallback. The description adds no parameter-level detail, which matches the baseline-3 rule when the schema does the heavy lifting.
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 resource (every domain registrar tracked) and the payload (WHOIS-privacy info plus tracked-TLD counts), which is a clear verb+resource statement. It does not explicitly differentiate itself from siblings like get_tld_prices or check_domain_availability, but the registrar-as-resource framing makes the distinction inferable.
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?
There is no when-to-use guidance, no prerequisite statement, and no mention of alternatives among the six sibling tools. An agent must infer from the name alone that this is a lookup of registrar metadata rather than a price or availability query.
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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