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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, idempotentHint=false), the description discloses the side effect (success means the domain serves the project with automatic HTTPS), the non-terminal failure state (result stays pending), and what a pending result carries (expected records plus a plain-language reason). That tells the agent this is an external-DNS-dependent, re-runnable mutation whose failure is informational rather than an error.

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 sentences, front-loaded with the action, then the sequencing constraint, then the failure/retry contract. No restatement of the title, no filler, and each sentence supplies information the agent needs to avoid a wrong call or a premature error report.

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?

The tool has 2 required params, full schema coverage, and an output schema, so return shape needn't be explained — yet the description still characterizes the pending payload at a high level. For a low-parameter, externally-dependent verification tool, nothing an agent needs to invoke it correctly is missing.

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% for both parameters, including the hostname format constraint, so the schema already carries the semantics. The description adds only the implicit constraint that the domain must already be claimed, which is contextual rather than parameter-level guidance. Baseline 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?

States a specific verb and resource ("Re-run the DNS check for a claimed custom domain") and positions itself relative to the sibling add_custom_domain, which it names as the prerequisite. An agent can distinguish this from add_custom_domain / remove_custom_domain without opening any schema.

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?

Explicit sequencing ("add_custom_domain first"), explicit expected-failure condition ("Failure is normal while DNS propagates"), and explicit retry guidance ("wait a few minutes and call again"). It tells the agent both when to call and how to interpret a negative result, which is exactly the ambiguity that causes retry loops.

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