Localize Apply

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

Annotations already cover safety and idempotency (readOnlyHint=false, idempotentHint=true, destructiveHint=false), and the description adds real behavior beyond them: out-of-spec locales are silently ignored, and the result shape is disclosed. It stops short of explaining merge/overwrite semantics on existing keys.

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?

Four terse, front-loaded lines: what it does, when to use, when not to, and what it returns. Every sentence earns its place with zero padding.

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 two-param, idempotent, non-destructive mutation with full annotation and schema coverage, the description covers trigger, exclusions, alternatives, and outcome. Nothing an agent needs to call it correctly is missing.

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% with two well-documented required params, so the schema already carries the burden. The description adds only the spec-locale filtering rule, which is behavioral rather than parameter syntax, so baseline 3 is appropriate.

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 and resource ('Merge translations into the in-app String Catalog') plus the scope restriction ('for the spec's app locales'), which separates it from the many other localization and metadata siblings.

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?

Explicitly names the trigger ('Use when: after translating UI strings'), the exclusion ('Not for: store listing copy'), and routes to the correct alternatives (metadata_render_listing / deliver_metadata).

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