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

Annotations already declare destructiveHint=true, openWorldHint=false, and idempotentHint=false, so the safety profile is covered. Beyond that, the description adds real behavioral context absent from the annotations: the duplicate-name case returns 'already-exists' and creates nothing, and the success case returns the project with its default locale and locales.

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, front-loaded with the trigger condition, followed by return/error behavior and the exclusion. No sentence is redundant and nothing is buried.

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?

An output schema exists so return values need no further explanation, yet the description still summarizes the meaningful returns and the failure mode. With full parameter coverage and annotations carrying the safety profile, nothing needed to call this tool 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%, so the schema already documents name, locales, and defaultLocale fully, including format and the fact that the default locale is added automatically. The description adds no syntax or format detail beyond that, so the baseline of 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?

The description states a specific verb and resource ('create a new localization project') and scopes it with the inputs that matter (name and languages). It also carves out the adjacent operation, so an agent can distinguish it from add_locale without opening either 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?

It gives an explicit trigger ('Use this when someone asks to create a new localization project') and a clear exclusion ('Not for adding a language to an existing project'). The exclusion implies add_locale but never names it, so routing is clear but not maximally explicit.

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