List Allowed Directories

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

The description adds valuable behavioral context beyond the readOnlyHint annotation by specifying that subdirectories within allowed directories are also accessible, which clarifies the scope of access. However, it does not mention other potential traits like rate limits or authentication needs, though the annotation covers the safety aspect adequately.

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 concise and well-structured, with two sentences that efficiently convey the tool's purpose and usage without any wasted words, making it easy to understand quickly.

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 the tool's simplicity (0 parameters, readOnlyHint annotation, and an output schema), the description is complete. It explains what the tool does, when to use it, and the scope of access, which is sufficient for an agent to invoke it correctly without needing additional details on parameters or return values.

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 parameters and 100% schema description coverage, the baseline is 4. The description adds no parameter-specific information, which is appropriate since there are no parameters, and it focuses on the tool's purpose and usage instead.

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 tool's purpose with a specific verb ('Returns') and resource ('list of directories that this server is allowed to access'), and distinguishes it from siblings by focusing on allowed directories rather than general directory operations like 'list_directory' or 'directory_tree'.

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 provides explicit guidance on when to use this tool ('to understand which directories and their nested paths are available before trying to access files'), including a practical context for usage and an implied alternative (use this before other file-access tools).

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