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

The description adds one meaningful behavioral detail beyond the annotations—that missing parent directories are created—while annotations already cover idempotency and non-destructiveness. It does not describe error behavior, output properties, or side effects, but the annotation coverage lowers the burden, making this adequate but not rich.

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?

The description is a single sentence that is directly actionable and front-loaded with the usage trigger. Every word adds value and there is no redundant phrasing.

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 directory-creation tool with full schema coverage, an output schema, and meaningful annotations, the description is nearly sufficient. It could be more complete by noting what happens when the directory already exists or mentioning the paths parameter for batch creation, but those are covered by annotations and schema.

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 parameters are already fully documented. The description only implies that path creation includes parent directories; it adds no additional meaning to the individual parameters beyond what the schema provides, so the baseline of 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?

The description clearly states the tool creates directories and includes missing parent directories, which is specific and distinguishes it from file-writing siblings. However, it is phrased as a usage instruction rather than a declarative definition, and it does not explicitly differentiate it from other creation-style tools beyond that.

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 gives an explicit condition for when to use the tool ('when the user asks to create a directory') and adds a useful detail about missing parent directories. It does not state when not to use it or mention alternatives, so it lacks the full when/when-not structure of a 5.

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