Disk usage

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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds value by specifying platform differences (df vs drive usage) and the 'allowed path' concept, which goes beyond the annotation. It does not contradict annotations, and the added context is useful.

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 a single, efficient sentence that front-loads the main purpose. Every word earns its place, with no filler or repetition. It is concise and well-structured.

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 tool with one optional parameter and an output schema, the description is mostly sufficient, but the phrase 'allowed path' is ambiguous—it does not define what 'allowed' means (e.g., permissions, path type, or allowed directory). The return format is covered by the output schema, but the missing clarification of 'allowed path' could confuse an agent. Given the tool's simplicity, this gap is notable but not fatal.

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 description coverage is 0%, so the description must explain the 'path' parameter. It mentions 'size of one allowed path,' which gives a hint that the path is used to retrieve its size, but it does not clarify that the parameter is optional (as indicated by the schema default ''), nor does it explain the default behavior when no path is provided. The description partially compensates but lacks full semantic detail.

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 function: 'Show filesystem usage' plus size of one allowed path. It is specific (verb 'Show', resource 'filesystem usage') and differentiates from siblings by noting platform-specific behavior (df on Linux/macOS, drive usage on Windows). No sibling tool has a similar purpose, so it stands alone.

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 contexts (displaying disk usage and path size) but does not explicitly state when to use this tool versus alternatives. There are no obvious sibling tools for disk usage, so the lack of explicit exclusions is acceptable, but it doesn't provide guidance on when not to use it or alternative approaches.

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