Mkdir

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

With no annotations, the description carries the burden of behavioral disclosure. It discloses a meaningful permission requirement, 'Requires FS_READONLY=false,' but does not explain what happens when the directory already exists or whether intermediate parents are created. The schema defaults hint at behavior, but the description itself is minimal.

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 extremely short: two sentences with no filler. The core action comes first, followed by the permission constraint. It is concise, though it sacrifices valuable behavioral and parameter guidance.

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?

Given an output schema exists and this is a simple tool, the description is minimally acceptable. It states what the tool does and the key permission requirement. However, it lacks context about default behavior for existing directories or parent creation, and the 0% parameter coverage leaves gaps that the description could have filled.

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 0%, and the description does not compensate by explaining 'path', 'parents', or 'exist_ok'. While 'path' is somewhat obvious, the meaning and effect of 'parents' and 'exist_ok' are left entirely to inference from their names and defaults.

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 action: 'Create a directory.' This is a specific verb plus resource and matches the tool name without ambiguity. It doesn't describe edge-case behavior, but the core purpose is unmistakable and distinct from the sibling file tools.

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 a necessary precondition, 'Requires FS_READONLY=false,' which helps the agent know when this tool is allowed. However, it does not explicitly compare against alternatives like write_file or move, so when-to-use versus siblings is only implied by the 'mkdir' semantics.

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