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

Annotations already declare the safety profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the bar is lower; the description adds genuine value by disclosing the negative scope (no email/password/delete) and the dashboard fallback. It still omits what happens to unmentioned fields and any auth/permission requirements.

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 tight sentences with zero filler; the capability is front-loaded and the boundary/redirect sentence follows immediately. Every clause earns its place.

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 two-parameter mutation with no output schema, the description covers what changes, what is off-limits, and where to go instead. It could add that omitted fields remain unchanged (implicit in the 'and/or' phrasing) and whether the updated settings are returned, but nothing critical 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% — both parameters are documented, including null-clears-name and the partial emailPrefs patch semantics. The description only restates the two settings generically, adding no syntax or format detail beyond the schema, so baseline 3 applies.

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+resource ('Update the account's display name and/or email notification preferences') and bounds the scope by naming what cannot be changed. The read counterpart get_account_settings is an obvious sibling, but it is never named, so differentiation stays implicit.

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?

Explicitly routes the agent away for the excluded operations: 'Cannot change email/password or delete the account — do that in the dashboard.' No exclusions are given for the covered operations or for when to read settings first, so it falls short of full when/when-not/alternatives coverage.

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