fs_mkdir

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

The description discloses a significant behavioral trait: the VM remains locked by this session and requires a subsequent vm_unlock call. This goes beyond the annotations, which only indicate read-only/idempotent/destructive hints. It adds real operational context that an agent needs to know.

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 two sentences: the first gives the purpose, the second gives a critical behavioral instruction. It is tightly worded, front-loaded, and every word earns its place with no filler.

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?

The core purpose and a key side-effect (locking) are covered, but the description omits details about parameter semantics, return values, and error behavior. Given the lack of an output schema, this leaves the agent with some uncertainty, though the operation is simple enough that a minimum-viable description is present.

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?

With 0% schema description coverage, the description was expected to explain the parameters. It does not mention 'path' or 'recursive' beyond the tool name. The semantics of 'path' (guest filesystem path) and 'recursive' (whether to create parent directories) are left to the agent's inference from standard mkdir behavior, which is not explicit.

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 begins with 'Create a guest directory,' a clear verb+resource statement that distinguishes this tool from filesystem siblings like fs_move, fs_delete, and fs_list. The action is unambiguous and the resource (a directory on the guest) is specified.

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?

No guidance is given on when to use this tool versus alternative fs operations. There are no explicit exclusion conditions or alternative tool references. The only usage-related note is the sequencing requirement to call vm_unlock after finishing, which is helpful but does not help with tool selection.

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