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

Annotations already declare the safety profile (destructiveHint=true, idempotentHint=true, readOnlyHint=false), and the description adds genuinely non-redundant semantics: omitted fields are preserved, explicit null clears nullable fields, and the sensitive-content boolean rejects null. What it omits is the consequence of destructiveHint=true (e.g., that clearing name/language fields is irreversible without a follow-up call) and any auth/scope requirement.

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 short sentences, zero filler, with the core purpose front-loaded and the patch/clearing rules immediately after. Every clause carries information the agent cannot get from annotations or the schema.

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?

Output schema exists, so return values need no explanation, and the patch semantics plus the null constraint cover the main traps for a 0-required-param mutation tool. The gap is around scoping and side effects of a destructive-flagged update — an agent still cannot tell whether this affects only the authenticated user or what permissions are needed.

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 all six parameters rely on the description, which supplies the crucial global patch rule and a carve-out for showUnassessedOrSensitiveContent ("cannot be null"). The remaining five fields (firstName, lastName, language, currency, measurementUnit) get no per-field meaning, though their names and the enum sets are largely self-explanatory. Partial compensation, not full.

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 pair ("Update your profile and preferences") that maps unambiguously to the account resource, and "your" makes clear it targets the caller's own account rather than another user. It does not explicitly differentiate itself from patch-style siblings like updateUserAddress or updateUserSearchFilter, but the resource distinction is obvious from the name and text.

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?

Describes the patch contract ("Omitted members are unchanged; null clears optional values"), which implicitly tells the agent how to invoke it, but never states when to prefer this over siblings such as getUserAccount for reads or updateUserSearchFilter for filter edits. No prerequisites or exclusions are given; usage is inferable rather than stated.

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