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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), and the description adds genuinely new behavioral context on top: long tables are truncated and report that fact, and text resolves via t(x) = player's table -> fallback table -> the key literal itself. The fallback-chain explanation tells the agent what it will actually observe at runtime, which the annotations cannot convey.

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 sentences, purpose front-loaded, no filler or restated boilerplate. The final sentence about resolution order is the longest and most tangential, but it earns its place by explaining why untranslated literals still render.

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?

There is no output schema, so the description must carry return-shape information, and it does: keys with default-language text, the configured locales, and truncation on long tables. Combined with the usage trigger and filter syntax, an agent has everything needed to call this correctly on the first try.

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%, so the baseline is 3; the description earns an extra point by making the 'prefix' parameter concrete with examples ('shop.', 'quest.') that show the expected key-namespace format. title_id is left unexplained, but its meaning is unambiguous from the schema.

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 states a specific verb and resource ('List the title's localization KEYS') and pins down scope precisely: default-language text plus the configured locales. It is clearly distinguishable from write-side siblings such as save_localization_keys. It does not explicitly contrast itself with the similarly named get_localization, which is the one sibling an agent could plausibly confuse it with.

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?

It gives an explicit trigger condition: 'Call it before writing any user-visible string so you reuse an existing key instead of inventing a second one for the same label.' That is strong, actionable when-to-use guidance, and the prefix-filter hint supports invocation. It stops short of naming the alternative tool (get_localization) or stating when not to call it.

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