fs_list

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe read operation. The description adds significant behavioral context beyond annotations by revealing that the VM remains locked by the session and that vm_unlock must be called afterward. This is a non-obvious side-effect/requirement not captured in the annotations.

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 short sentences that front-load the core action ('List a guest directory') and immediately follow with a necessary caveat about unlocking the VM. Every word earns its place; no fluff or redundancy.

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 list tool with two parameters and rich annotations, the description covers essential context: the target is a guest directory, recursion is optional, and the VM lock must be released afterward. It does not mention the return format, but given the name and action, that is reasonably implied. The lock-unlock note adds completeness that goes beyond typical list tools.

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 schema description coverage at 0%, the description must compensate, and it partially does: 'guest directory' clarifies the `path` parameter, and 'optionally recursively' explains the `recursive` boolean. However, the description does not add details about path format, error behavior, or what the listing returns, leaving the semantics shallow. The names are self-explanatory, but the description adds just enough to reach a 3.

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 uses a specific verb 'List' and a clear resource 'guest directory' with the optional recursive qualifier. It clearly distinguishes fs_list from sibling tools like fs_stat, fs_mkdir, or fs_delete, making its purpose immediately obvious.

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 provides important contextual usage guidance by noting 'VM remains locked by this session; call vm_unlock when finished.' This tells the agent when it needs to follow up with vm_unlock, which is a clear usage directive. However, it does not explicitly name alternatives or describe when not to use this tool, so it falls short of a 5.

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