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

Annotations already declare destructiveHint=true, idempotentHint=false and readOnlyHint=false, so the safety profile is covered. The description adds which attributes are affected, but says nothing about reversibility, whether turning tracking off loses data, or required permissions beyond what the annotations imply.

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 tight sentence with the resource and the two mutable attributes front-loaded. No filler, no repetition of 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 destructive, non-idempotent mutation with no output schema, the description is thin: it does not say whether `purposes` replaces or merges existing values, what turning tracking off implies, or what a successful update returns. Annotations carry the safety signal, so the gaps are notable but not fatal.

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?

The schema leaves the `tracking` boolean entirely undescribed, and the description fills that gap by explaining it is the toggle for both open and click tracking. It also names the two mutable concepts matching `purposes` and `tracking`. It adds little syntax beyond the already well-documented domainId.

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 (change) and resource (email domain) and names exactly which fields are mutable (purposes, open/click tracking). This distinguishes it from the many add/remove/check/verify domain siblings, but it never explicitly contrasts itself with them.

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 only says what the tool does, with no when-to-use context, no prerequisites, and no mention of alternatives such as register_mail_domain or get_email_setup. The agent must infer that this is the edit path for an existing domain.

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