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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so safety profile is covered. The description adds real context beyond them: the locale is auto-enabled on the set as a side effect, the fallback model, and plan/auth requirements. That is meaningful disclosure, though it doesn't spell out precisely what storing overrides destroys.

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 front-loaded sentences; the core action and scope lead, then the fallback rule, then prerequisites. Every clause carries information and nothing is redundant.

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 mutation tool with no output schema, the description covers purpose, fallback behavior, side effects (locale auto-enable) and access prerequisites, which is nearly everything an agent needs to invoke it correctly. Only a fuller account of what existing overrides are replaced would make it complete.

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 locale, set_id and entries are already well documented in the schema, including the sparse-override keying and wholesale replacement semantics. The description only gestures at override types ('text copy, localized captures/images') without adding format or syntax detail, so it sits at the baseline 3.

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 (Write) and recognizable resource (a locale's translation overrides for screens in a screenshot set), and clarifies scope with examples '(text copy, localized captures/images)'. An agent can distinguish this from siblings like sonar_update_screenshot or sonar_update_screenshot_set without opening their schemas.

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 clear context for when to use it (writing per-locale overrides) and the governing rule 'geometry and styling always come from the source layout; anything not overridden falls back to it', plus prerequisites (Indie plan, authorized account or write-scope key). It does not name when-not to use it or point to an alternative sibling, so it stops short of a 5.

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