list_registrarsList active TLD-List registrar IDs with substring filtering and pagination to retrieve exact IDs for use in other TLD-List tools.
List active TLD-List registrar IDs with substring filtering and pagination. Use these exact IDs in other tools.
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | ||
| query | No | Case-insensitive registrar ID substring. | |
| offset | No |
Changes observed during successful MCP inspections.
v0.1.3Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and non-destructive, covering the safety profile. The description adds two genuinely useful facts beyond that: results are restricted to *active* registrars and the return is IDs (not full registrar records). That's modest added context, not enough for a 4.
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 tight sentences, front-loaded with the action and scope, and ending with the actionable instruction about ID reuse. Nothing wasted.
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, zero-required-param list tool with no output schema, the description conveys what is returned (registrar IDs) and the filtering/pagination behavior. It leaves the exact ID format and result ordering unstated, but that is a minor gap.
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 only 33% (only 'query' is documented), yet the description merely alludes to 'substring filtering and pagination' without adding format, default, or limit/offset semantics. It adds no meaning beyond the schema, so it neither compensates for the coverage gap nor drops below the baseline.
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 and resource ('List active TLD-List registrar IDs') plus the scoping mechanisms (substring filtering, pagination), which separates it from list_tlds and the search/compare siblings. It doesn't explicitly name which sibling to prefer, so it stops short of a 5.
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?
'Use these exact IDs in other tools' gives downstream usage context, implying this is a lookup step feeding tools like check_domain or compare_registrars. However, it gives no guidance on when to use this versus list_tlds or search_tld_variants, so usage is only implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.