image_disk_usage

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

With no annotations, the description must disclose behavior. It declares the operation as read-only via '[READ]' tag and specifies the data source and output fields (total, shared, reclaimable). It does not detail potential errors, permissions, or side effects, but for a simple read operation this is adequate.

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, using two short sentences. It front-loads the read indicator and immediately states the purpose. No unnecessary words or redundancy; every phrase adds value.

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 simplicity (one optional param, no output schema), the description covers the essential aspects: source, data fields, and parameter usage. It does not specify the return format (e.g., numbers, object), but for a straightforward read this is acceptable.

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 schema has 0% description coverage, so the description must compensate. It explains the 'target' parameter as 'Target name from config; omit for the default.', adding meaningful context beyond the schema's type and default. This is sufficient for a single optional parameter.

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 verb 'READ' and the resource 'image disk usage', specifying it comes from system/df and returns total, shared, reclaimable. This distinguishes it from sibling tools like system_df (system-wide) and list_images (listing), making the purpose unambiguous.

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 querying image disk usage but provides no explicit guidance on when to use this tool versus alternatives like system_df or inspect_image. No exclusion criteria or alternatives are mentioned, though the context of siblings helps infer its niche.

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