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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=true, idempotentHint=true), so the bar is lower. The description adds real value beyond that: the non-sensitive scope and the intentional exclusion of email/password/billing, which an agent would otherwise have to discover by failure.

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?

Front-loaded and short, but the opening is redundant: "Update account settings. Update non-sensitive account settings... Writable account settings." says the same thing three ways, and "Provide at least one" is stated without connecting it to the parameter list.

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?

With no output schema needed, a 6-param optional-only update tool whose annotations cover safety, the description supplies the missing pieces: what scope is writable and what is deliberately not. Only a note on the destructive/idempotent implications of clearing values is absent.

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%, so the schema already documents all six parameters, including the timezone null-clears-to-UTC behavior. The description only cites visit_own_sites and timezone as examples and adds no syntax or format detail beyond the schema; 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 account settings) and scopes it as non-sensitive settings only, naming example fields. It implicitly separates from get_account and create_* siblings, though it never names a sibling explicitly.

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?

Gives a clear precondition ("Provide at least one" setting) and explicit exclusions (email, password, billing are not editable via the API), which steers the agent away from unsupported attempts. No explicit routing to an alternative tool for those excluded fields.

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