disk_usage

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

With no annotations, the description fully covers behavioral traits: it declares read-only operation ('Read-only'), details the underlying commands (df, du, sudo), excludes pseudo-filesystems, and mentions error conditions ('df_not_available'). The return format is also described, providing comprehensive transparency.

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 extremely concise: two sentences plus a brief metadata line. It front-loads the core purpose and includes all necessary details without any redundant language.

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 complexity, the absence of an output schema, and no annotations, the description provides complete context: inputs, behavior, return structure, and error handling. No gaps remain.

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 covers both parameters (instance_id, top_n) with descriptions, achieving 100% coverage. The description adds no new meaning beyond the schema, meeting the baseline of 3.

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 purpose: 'Per-filesystem disk usage on one instance plus the top directory consumers under the fullest mount.' It specifies the resource (disk usage on one instance) and the action (listing filesystems and top consumers), distinguishing it from sibling tools which cover different domains.

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 for checking disk usage but does not explicitly state when to use this tool versus alternatives or when not to use it. No exclusions or comparisons to sibling tools are provided, so the guidance is minimal.

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