du

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

With no annotations, the description carries full burden, and it does disclose useful traits: it wraps Sysinternals DU, runs in verbose mode, and implies a one-time EULA acceptance (echoed by accept_eula). However, it omits permission requirements, read-only nature, and any rate/timeout behavior for a filesystem-scanning tool.

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?

Front-loaded purpose sentence followed by a brief notes block and a return-format section; every line is short and earns its place. Minor redundancy with the declared output schema in restating the return shape.

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 directory-scanning tool with 100% schema coverage and an output schema, the definition covers purpose, underlying implementation, and return shape adequately. Only the when-to-use guidance versus du_quick is absent.

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%, so all three parameters (path, n_children, accept_eula) are already documented in the schema to the same depth the description offers. The description adds no parameter syntax or default details beyond that baseline.

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?

States a specific verb+resource ('Show disk usage for a directory tree') and adds a scope qualifier ('broken down by subdirectory'). It does not explicitly name or contrast with the obvious sibling du_quick, so sibling differentiation is only implied by the verbose mode note.

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 mention of 'verbose (-v) output for per-directory breakdown' implies a detailed-analysis use case that contrasts with a quick variant, but the description never names du_quick or states when to prefer this over it. Usage 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.