List Depot usage per project

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

The annotations already declare readOnly, idempotent, and non-destructive behavior, and the description adds no contradictions. It further explains behavioral details such as sorting by layer cache size, default time window of 30 days, and the dependency between startAt and endAt, making the tool's runtime behavior fully transparent.

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 concise and well-structured across three sentences. It avoids redundancy for the most part, though the repeated pattern 'use for ... for ... use' is slightly verbose but still efficient. Overall, every sentence adds value without unnecessary 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?

The description covers the tool's purpose, usage scenarios, distinguishing features from siblings, and important behavioral nuances such as sorting, defaults, and pagination. Since an output schema is provided, the lack of return value details is acceptable, making the description contextually 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?

The schema already covers all four parameters with 100% coverage, so the baseline is 3. The description adds useful context about defaults (30 days) and pagination (re-call with pageToken), which enriches parameter understanding beyond the schema alone.

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 action (List), the resource (Depot usage per project), and the scope (build count, build time, layer cache size) in one call. It also distinguishes this tool from sibling tools by focusing on per-project usage, which makes its 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?

It explicitly states when to use this tool (for questions like which project holds the most cache) and contrasts it with sibling tools (depot_get_usage for minutes billed/saved, depot_get_cache_summary for one project's cache health). It also provides pagination guidance with nextPageToken, giving clear actionable instructions.

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