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

With annotations already declaring readOnlyHint false and destructiveHint true, the description adds genuinely useful behavior: it operates in the authenticated organization and refuses duplicate project names, which also explains the non-idempotent nature. It does not over-explain beyond what the annotations and schema already 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?

Two short sentences, front-loaded with the core action and followed by the key constraint. Every clause earns its place and there is no redundant restatement of the title or schema.

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 simple creation tool with a 3-parameter schema, full property descriptions, and an output schema, the description covers the essential semantics: what is created, how locales are supplied, duplicate behavior, and organization scope. A minor gap is that it does not mention what happens when the defaultLocale is also listed in locales, but that is not necessary for correct invocation.

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?

The input schema provides 100% description coverage for name, locales, and defaultLocale, including the automatic addition of the default locale when omitted. The description reinforces the default-plus-optional structure but adds no parameter-specific detail beyond 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 opens with a specific verb+resource ('Create a MultiLocale project') and scopes the operation to a default locale plus optional additional locales. This clearly distinguishes it from sibling tools like add_locale and update_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 intended use is clear: invoke this to create a new project, with a uniqueness guard for duplicate names. It does not explicitly route to alternatives such as update_project or add_locale, but the create semantics and sibling context make the selection unambiguous enough without exclusions.

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