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

Annotations already signal a non-read, non-destructive operation, and the description adds meaningful behavioral context: the backend performs DNS provider detection and returns configuration instructions. This helps the agent anticipate the tool's flow without contradicting the annotations.

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 concise sentences deliver the core purpose and a key behavioral detail without any filler. The most important information is front-loaded in the first sentence.

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 single-parameter tool with a rich output schema and annotations, this description is complete. It explains what the tool does, what happens during execution, and what the user will need to do afterward, leaving no critical gap for 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?

There is only one parameter and the schema already documents it fully (type, required, description, example). The description does not add further parameter-level detail, but no additional explanation is strictly needed given 100% schema coverage.

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 uses a specific verb and resource: 'Add a custom domain.' It clearly states the domain is custom and explains the core outcome (backend detects DNS provider and returns needed DNS records), which differentiates it from sibling tools like list_domains and remove_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 intended use is implied through the phrase 'Add a custom domain,' and the mention of DNS records gives useful context. However, it does not explicitly state when to choose this tool over alternatives, nor does it mention prerequisites or limitations.

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