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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the household-wide scope of the effect, but says nothing about whether the change is persisted immediately, who may invoke it, or whether existing content (recipes, notes) is affected. With annotations present, a 3 is appropriate.

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?

One short sentence, front-loaded with the verb and effect, followed by the allowed values. Nothing is wasted and no clarification is buried late.

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 one-parameter, fully documented setting toggle with annotations covering mutability and idempotency, the description is largely sufficient. Minor gap: no indication of the response or how to confirm the new language took effect, though no output schema exists to cover that.

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% and the single parameter already carries a BCP-47 enum with per-value glosses. The description repeats those same three codes, adding no new meaning such as default behavior when omitted (it is required) or how the setting interacts with per-member language preferences. 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?

The description gives a specific verb ('Set') plus the exact resource ('the language Bryti uses with the household') and enumerates the three accepted values, so the agent knows precisely what changes. It stops short of naming the sibling that overlaps in scope (update_household_settings), so the differentiation is implied by name only rather than stated.

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 implied by the narrow, self-evident purpose, but there is no explicit statement of when to prefer this tool over update_household_settings or who is entitled to change household-wide settings. No exclusions or prerequisites are given.

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