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

The annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds useful behavioral context by noting that unverified domains are included along with DNS setup instructions and status tags. However, it does not discuss pagination behavior, workspace access assumptions, or other operational details beyond what annotations and schema provide.

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 efficient sentence and front-loads the core retrieval purpose. The only minor waste is the redundant 'Get Custom Domains -' prefix, which largely restates the title.

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 retrieval tool with complete schema descriptions, read-only annotations, and an output schema, the description supplies enough context about what is returned, including unverified domains and DNS setup details. Usage guidance remains the main gap, but the definition is otherwise complete for correct invocation.

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 skip, limit, and workspace_id are already documented in the input schema. The description only indirectly reinforces the workspace scope and adds no new semantics for pagination or workspace selection. Baseline 3 is appropriate when the schema fully carries parameter 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?

The description states a specific verb and resource: 'Retrieve custom tracking domains for the workspace.' It also clarifies that unverified domains and DNS setup/status details are included, which makes the scope more precise. It does not explicitly differentiate from any sibling, though none of the listed siblings appears to cover custom domains.

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 explains what the tool retrieves but gives no guidance on when to use it, when not to use it, or which alternatives to prefer. The implied use case is clear only because the tool name is self-explanatory, not because the description provides usage rules.

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