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

Annotations already flag destructive=true, and the description adds meaningful behavior context: removal via empty string, DNS verification requirements (CNAME/A vs TXT), and the distinction between custom domain and subdirectory modes. It stops short of describing post-removal effects, but the annotation covers the destructive nature.

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?

Three short sentences front-load the core purpose and then convey usage modes, DNS requirements, and removal behavior. There is no filler or repetition.

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?

Given the output schema exists, the description covers all necessary decision points: which mode to use, what DNS prerequisites apply, how to remove a domain, and the role of domain_slug. An agent has the full picture needed 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?

Although the schema already documents all three parameters, the description adds the crucial relationship semantics: domain alone for custom domains, domain plus domain_slug for subdirectory, and empty domain for removal. This is exactly the kind of parameter interaction an agent cannot reliably infer from the schema alone.

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 opens with a specific verb and resource: 'Configure or remove a blog's custom domain.' It clearly distinguishes the tool from generic update_blog/update_blog_metadata siblings by making domain configuration the sole focus.

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?

It gives explicit mode-based guidance: use domain alone for custom domains with CNAME/A DNS, use domain plus domain_slug for subdirectory hosting with TXT DNS, and pass an empty string to remove. This tells an agent exactly when and with which parameters to invoke the tool.

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