List custom domains

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The readOnlyHint annotation already communicates that this is a safe read operation. The description adds value beyond annotations by specifying that the result includes SSL status and that the domains are scoped to an aCDN resource. This is useful context, though it does not describe pagination or response structure.

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 a single, front-loaded sentence that communicates the core purpose and an additional detail (SSL status) with no wasted words. Every element earns its place.

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 read-only list tool with one parameter, strong annotations (readOnlyHint, openWorldHint), and no output schema, the description covers the essential scope and return detail. It is complete enough for an agent to select and invoke the tool correctly without further context.

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 schema already provides a 100% description coverage for the single parameter, resource_id, as 'aCDN resource (pull zone) ID'. The description does not add syntax or format details beyond the schema, so the baseline of 3 is appropriate.

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 states a specific action ('List') and resource scope ('custom domains attached to an aCDN resource'), and adds useful detail ('including SSL status'). This clearly distinguishes it from sibling tools like list_vcdn_domains or search_custom_domains, which target different resource types or purposes.

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 context: it is used to list custom domains for a specific aCDN resource. However, it does not explicitly mention when not to use it or name alternatives (e.g., search_custom_domains). The scope is clear enough to infer the primary use case, so it earns a 4 rather than a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.