List directory

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering safety. The description adds value by disclosing the exact output fields (type, size, modified time, mode), which goes beyond what annotations state. This is useful behavioral transparency for a read-only listing operation.

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?

A single, front-loaded sentence with zero filler. It states the action, scope, and output details efficiently, earning its place entirely.

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 one-parameter tool with rich annotations, the description adequately covers what it does, what it returns, and its read-only nature. No output schema exists, but the description specifies return fields. It is sufficient for an agent to invoke it correctly without further clarification.

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 100%, with the path parameter fully documented ('Directory to list'). The description does not add any additional meaning or syntax beyond the schema, so it meets the baseline for high coverage without needing compensation.

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 a specific action ('List files and subdirectories') and the target resource (directory), and specifies the returned attributes (type, size, modified time, mode). This clearly distinguishes it from siblings like read_file (content) and search_files (search), even without naming them.

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 through its clear purpose—list directory contents—but provides no explicit when-to-use vs. alternatives (e.g., read_file for file content, list_roots for root dirs). No exclusions or conditions are given, so agents must infer the appropriate context from the name and description alone.

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