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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the safety profile is known. The description adds genuinely useful context beyond that: the save is PARTIAL (only one field is overwritten, sibling fields survive), and it explains the client resolution order t(x) = own table -> fallback -> key, which clarifies the consequences of changing default/missing-key settings. It stops short of mentioning permission requirements or how the write is validated.

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-loads the critical constraint ('PARTIAL SAVE: writes ONLY the Localization field') in the first clause. Most sentences earn their place by routing the agent away from the wrong tool, but the closing narrative about literal names and 'text changes more often than balance' is somewhat digressive and partly duplicates schema text.

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 nested-object mutation with no output schema and no annotation-level detail on scope, the description covers what is written, what is preserved, why tables live elsewhere, and how resolution behaves — enough for correct invocation. It does not discuss the response, but with no output schema that is a minor omission.

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 every nested field (Locales, IsEnabled, DefaultLocale, MissingKeyMode, MaxEntriesPerLocale, MaxValueLengthBytes) is already richly documented in the schema. The description restates the same concepts (locales offered, default/fallback, missing-key rendering, store limits) without adding syntax or format detail, so the 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 precise verb+resource+scope: 'writes ONLY the Localization field of TitlePublicConfigurationModel; all other v1/v2 fields stay untouched.' It explicitly distinguishes itself from the translation-table tools (save_localization_keys / TitleLocalization), so an agent can tell it apart from its closest siblings without opening a schema.

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 explicit when-to-use and when-not: this section is for locale list/default/missing-key behaviour and store limits, while 'Add or edit translations through the Localization endpoints, not through this section.' It also names the sibling collection (TitleLocalization) where the tables live, leaving nothing to inference.

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