Get time by activity category

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

With no annotations provided, the description carries the full burden. It discloses that the tool performs a roll-up aggregation, uses a fixed taxonomy, and has a fallback mapping (unmapped apps go to 'other'). This covers the key behavioral traits for a read-only aggregation tool. It doesn't detail error handling or output formatting, but those are not critical for this type of operation.

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 exactly two sentences, front-loaded with the core action and taxonomy list. The second sentence adds a necessary usage note about label usage and the 'other' fallback. There is no redundant information or fluff, making it highly efficient.

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 that all parameters are optional and thoroughly described in the schema, and the tool is a simple read aggregation with no output schema, the description covers the essential behavioral details: it aggregates by category, uses a specific taxonomy, and handles unmapped apps. It is complete for an agent to understand and invoke the tool correctly.

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 input schema provides comprehensive descriptions for all 5 parameters, achieving 100% coverage. The description adds no parameter-specific information beyond what the schema already states (e.g., device filters, period formats, hour ranges). Per the rubric, with high schema coverage the baseline is 3, and the description does not need to compensate further.

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 tool's function: it 'rolls up app totals into Vetroscope activity categories', listing the exact categories (coding, creative, etc.). This is a specific verb+resource (app totals to categories) and distinctly differs from sibling tools like get_app_breakdown (per-app breakdown) or get_tag_breakdown (tag-based). The taxonomy reference to Charts and Settings reinforces its unique scope.

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 provides context by mentioning the same taxonomy as Charts and Settings, implying this is the canonical category aggregation. It also instructs to 'prefer category labels from the result verbatim' and notes that unmapped apps land in 'other'. However, it does not explicitly mention when to use this over get_app_breakdown or get_device_breakdown, or provide exclusions, so it lacks explicit alternatives.

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