Filesystem MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool returns absolute paths of directories the server can read/write, which is useful. However, it doesn't address critical behavioral aspects such as whether this requires specific permissions, if the list is cached or real-time, potential rate limits, or error conditions. For a tool with zero annotation coverage, this leaves significant gaps in understanding its operational traits.

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 highly concise and well-structured, consisting of two sentences that front-load the purpose and then specify the return type. Every sentence adds value without redundancy, making it easy to parse and understand quickly, with no wasted words.

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 low complexity (0 parameters, no annotations, but with an output schema that defines the return type), the description is mostly complete. It clearly states what the tool does and what it returns, and the output schema handles return value details. However, it lacks behavioral context like permissions or caching, which would enhance completeness for a tool with no annotations.

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?

The input schema has 0 parameters with 100% coverage, so the schema fully documents the lack of inputs. The description doesn't need to add parameter details, but it does clarify the tool's purpose and output, which is appropriate. Since there are no parameters to explain, a baseline of 4 is justified as the description effectively compensates by focusing on the tool's function.

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 specific action ('List all allowed directory roots') and resource ('for filesystem operations'), distinguishing it from siblings like list_directory (which lists contents of a specific directory) or directory_tree (which shows hierarchical structure). It precisely defines what the tool does without being vague or tautological.

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 implies usage context by mentioning 'allowed directory roots for filesystem operations,' suggesting this tool helps determine where operations are permitted. However, it lacks explicit guidance on when to use it versus alternatives like list_directory or directory_tree, and doesn't specify prerequisites or exclusions, leaving usage somewhat inferred rather than clearly defined.

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