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

The annotations already declare idempotentHint=true and destructiveHint=true, so the safety profile is partly carried by structured data. The description does add real context beyond them by naming the scope of effect (panel, emails, notifications) and by clarifying that Dana's reply language is independent of this setting. It does not, however, explain why the operation is flagged destructive or whether the change takes effect immediately, leaving the most consequential annotation unexplained.

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 short sentences with the action and allowed values front-loaded and no filler. The second sentence about Dana's reply language is slightly tangential but earns its place by preventing a plausible misinterpretation.

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 one required enum parameter, full schema coverage, an output schema and annotations present, the description covers what an agent needs to invoke it correctly. It is only marginally short on scope questions the agent might still have, such as whether the setting is per-user or workspace-wide and whether the effect is immediate.

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 coverage is 100% and the single enum parameter already documents en/fa with the right-to-left note for Farsi. The description only restates 'English or Farsi' and adds no format, casing, or default-locale guidance, so the baseline of 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?

The description names a specific verb and resource (change the user's language) and enumerates the affected surfaces: panel, emails and notifications. It is clear on its own, though it does not distinguish itself from the nearby preferences.update sibling, which plausibly overlaps.

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?

Usage is only implied: an agent can infer 'call this when the user asks to switch to English or Farsi', but there is no explicit when-to-use, no mention of preferences.update/preferences.read as alternatives, and no stated preconditions (e.g., whether this is per-user or org-wide, whether it requires admin rights).

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