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

Annotations already mark this as destructive and idempotent, so the description does not need to restate that. It adds beyond the annotations by explaining a non-obvious design invariant: project names cannot be changed because phrases reference the project name. It also signals that the locale list replacement is complete, not additive, which is important destructive context.

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?

Two sentences with no filler. The primary action is stated first, and the critical project-name invariants is placed second. Every word earns its place.

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?

The description plus the 100% schema coverage and annotations provide most of what an agent needs: what can be updated, the fact that project name stays fixed, and the destructive/idempotent nature. The only notable gap is the lack of explicit guidance about using add_locale versus update_project for locale changes, but the schema's 'complete replacement list' language mitigates this.

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 the description is not required to carry param details. It does name the high-level update targets (default locale, complete locale list, translation context), which maps to defaultLocale, locales, and context. But it adds no semantics beyond the schema, such as the requirement that defaultLocale be in the locales list or that the locales param is a complete replacement.

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 names a specific verb (Update), a specific resource (MultiLocale project), and exactly which aspects can be changed: default locale, complete locale list, and translation context. It also distinguishes itself by explicitly stating that project names are intentionally not changed, which separates it from any project-naming operation and from sibling tools like add_project.

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?

The description states what the tool can do and gives an explicit when-not: project names are intentionally not changed because phrases reference the project name. This is a clear exclusion. However, it does not explicitly contrast with add_locale or other sibling tools, so an agent must infer that add_locale is the better choice for adding a single locale rather than replacing the complete locale list.

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