fs_list

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

Annotations already indicate readOnly, idempotent, and non-destructive behavior. The description adds a meaningful behavioral side effect beyond annotations: the VM lock is retained by this session and requires vm_unlock. This is valuable context for safe agent behavior.

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 sentences with no filler. The primary operation is front-loaded, and the critical lock-release warning is placed second. Every sentence earns its place.

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 read-only list operation, the description covers the main action, recursive option, and lock state. It does not describe the return format, but the tool's name and 'List' imply a listing, and no output schema exists to do so.

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 only 33%, with path and recursive lacking descriptions. The description adds useful meaning by identifying path as a guest directory and recursive as optional recursion, but it does not compensate fully for path format, required existence, or error behavior.

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 and resource: 'List a guest directory' with an optional recursive flag. This clearly distinguishes fs_list from sibling tools like fs_move, fs_delete, and fs_stat, and the name/title reinforces the operation.

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?

It clearly states the operation and the optional recursive behavior. It also gives crucial lifecycle guidance by warning that the VM remains locked and instructing the agent to call vm_unlock when finished, though it does not explicitly discuss alternatives or when not to use this tool.

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