List Directory

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

Annotations already declare readOnlyHint=true and a closed world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the [FILE]/[DIR] prefix convention for output and the allowed-directories restriction. It omits whether the listing is recursive or paginated, which matters next to directory_tree.

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?

Four sentences, front-loaded with the action and output convention. 'This tool is essential for understanding directory structure' is slightly promotional filler, but nothing is redundant enough to impede selection.

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?

An output schema exists, so return values need not be re-explained, and the description sensibly adds only the [FILE]/[DIR] formatting cue that the schema may not convey. Annotations carry the safety profile. The one real gap is recursion/pagination behavior relative to directory_tree, which a careful agent would want.

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 coverage is 0% for the single 'path' parameter, so the description must compensate. It says the listing is for 'a specified path' and that the tool works only within allowed directories, which hints at path scoping but never says whether absolute vs relative paths are expected or how to discover allowed roots. Partial compensation only.

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?

Names a specific verb and resource ('Get a detailed listing of all files and directories') and defines the scope as a single specified path. It stops short of distinguishing itself from the very close siblings list_directory_with_sizes and directory_tree, so the agent must infer the boundary.

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?

'Essential for understanding directory structure and finding specific files' implies the use case, and 'Only works within allowed directories' is a real constraint. But it never says when to prefer this over list_directory_with_sizes (sizes), directory_tree (recursion), or search_files (pattern matching), so the routing decision is left to inference.

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