system_df

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

readOnlyHint=true already establishes this as a safe read, so the '[READ]' prefix is largely redundant. The description does add real value by enumerating what the breakdown covers (images, containers, volumes, build cache), which tells the agent the scope of the returned data.

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 with the core operation and its categories, then the arg, with no filler. Slightly formulaic Args block, but every line earns its place.

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, but the description names the categories of data returned, which is sufficient for an agent to know what it gets back. A one-parameter read-only tool is adequately covered; only multi-tool disambiguation is missing.

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 carry the parameter meaning, and it does: 'target: Target name from config; omit for the default.' That explains provenance and the omit-for-default behavior that the schema only implies via default=null.

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 resource and verb-like operation ('Disk-usage breakdown') and enumerates the four categories reported (images, containers, volumes, build cache). This is clearer than a bare name, though it does not distinguish itself from nearby siblings like image_disk_usage or image_and_volume_bloat.

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?

Only guidance given is about the target parameter default; there is no when-to-use or when-not-to-use guidance, and no routing to alternative disk-usage siblings such as image_disk_usage or image_and_volume_bloat.

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