disk_usage

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

With no annotations, the description carries the full burden and delivers: read-only guarantee, exact collection mechanics (df bytes+inodes, pseudo-filesystems excluded, depth-2 du), the sudo -n fallback, and the error case df_not_available. This is unusually rich behavioral disclosure for a diagnostic 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?

Three dense sentences with the primary scope front-loaded, then mechanics, then return shape and errors. No filler; every clause carries information.

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 exists, yet the description inlines the exact return JSON (filesystems fields, fullest_mount, top_consumers) and enumerates the failure mode. For a two-parameter read-only tool this is fully complete.

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 both parameters (including the top_n default and range) are already documented in the schema. The description implies top-consumer behavior but adds no syntax or selection meaning beyond the structured fields.

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 ('per-filesystem disk usage on one instance') and adds the secondary deliverable (top directory consumers under the fullest mount). It is clearly scoped to a single instance, distinguishing it from fleet-wide health tools. No sibling tool overlaps this disk resource.

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?

Usage is strongly implied (disk-pressure investigation) but there is no explicit 'use this when…' statement, no exclusions, and no named alternative. The read-only nature guides intent somewhat, but the agent must infer when to reach for this versus get_server_memory or fleet_health_snapshot.

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