Create a directory

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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral fact — that parent directories are created by default — but omits what happens when the target already exists and recursive is false (error vs. success) and any permission/auth requirements.

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, zero filler, with the core action front-loaded and the notable default behavior immediately after. Nothing is wasted.

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-parameter, non-destructive, idempotent filesystem tool with full schema coverage and no output schema, the description covers what it creates and the parent-directory default. The only real gap is failure behavior when the directory already exists with recursive=false, which is a minor omission.

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%, and the 'recursive' property already documents both 'Create parents' and 'Default true', so the description largely restates structured data. It adds no format, path-style, or absolute-vs-relative semantics 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 states a specific verb and resource ('Create a directory'), which is unambiguous against filesystem siblings like delete_path, list_dir, or write_file. It does not explicitly name or differentiate itself from any sibling, but the operation is distinct enough that an agent would not confuse it.

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 no when-to-use guidance, no prerequisites (e.g., permissions), and never mentions alternatives. It does not say whether to prefer mkdir over letting write_file create parents, nor when recursive behavior should be turned off.

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