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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds that it reports activation state and required DNS records, which is useful return-behavior context, but it omits any auth, rate-limit, or failure-mode details.

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?

A single front-loaded sentence that states the action, the object, and the diagnostic output with zero filler.

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, single-parameter read-only diagnostic tool whose annotations already cover the safety profile, the description is largely sufficient and even summarizes the return content in lieu of an output schema. It falls short only on explaining the identifier it expects.

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 0%, so the description is the only place parameter meaning could be conveyed, yet it never mentions customDomainId or how to obtain it. The name and uuid format make the parameter inferable, but the description does not compensate for the coverage gap.

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 ('Diagnose') and resource ('connected custom domain') and even names what it inspects ('activation state and required DNS records'). This distinguishes it from siblings like connect_custom_domain and verify_custom_domain, so an agent can tell what the tool is for without opening the 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?

The phrase 'a connected custom domain' implies the tool applies after a domain is connected, giving implied usage context. However, it never states when to use this versus verify_custom_domain or get_integration_status, and offers no exclusions or prerequisites.

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