Docker's disk usage

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

Annotations already establish readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by scoping exactly which Docker resources are measured and noting the reclaimable-space angle, giving the agent a clear picture of what the read returns. No auth or rate-limit notes, but none are needed for a local read-only inspection.

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?

A single front-loaded sentence that states the resource first and the scope second. Every clause earns its place with no filler.

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 zero-parameter, read-only reporting tool with an output schema already defining the return shape, the description supplies everything an agent needs: what is measured and how it relates to the prune action. Nothing essential 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?

The tool takes zero parameters, so the baseline is 4. The schema is empty with nothing to misinterpret, and the description correctly implies no arguments are needed to obtain the report.

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?

Names a specific resource (Docker disk usage) and enumerates exactly what is measured: images, containers, volumes, and build cache. It implicitly differentiates from the prune sibling by framing prune as the action that reclaims the reported space, though it never states outright that this tool only reports rather than reclaims.

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 mention of space that 'could be reclaimed by prune' implies the follow-up workflow, but there is no explicit when-to-use/when-not guidance or direct callout of the prune tool. Usage is left to inference.

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