core_du

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

No annotations provided, so description carries full burden. It discloses the default directory but lacks details on side effects (read-only?), error handling for non-existent paths, or performance characteristics. Minimal behavioral insight beyond the basic 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?

Single sentence with a dash, front-loaded and no fluff. Could be slightly more structured but remains efficient and clear.

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?

No output schema and description only states 'disk usage statistics' without specifying format or fields. Given the tool returns data, the description is incomplete; it doesn't hint at what the response looks like.

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% for all three parameters. The description adds no new meaning beyond what the schema provides for 'dir' (repeating the default) and does not mention '_async' or '_group'. Baseline of 3 is appropriate.

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 'Report disk usage' with a specific verb and resource, and indicates it returns statistics for a local directory. It distinguishes from sibling tools like core_disks by focusing on directory usage rather than listing disks.

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?

No guidance on when to use this tool versus alternatives such as core_disks or operations_size. The description does not provide context for appropriate usage or prerequisites like directory existence.

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