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

Annotations already carry the safety profile (readOnlyHint=true, openWorldHint=true). The description adds genuine behavioral value by disclosing default behavior when parameters are omitted (metric defaults to distance, groupby to true). It does not describe the output shape or limits, but with annotations covering safety, a 3 is appropriate.

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?

Two sentences, front-loaded with the core operation. It is slightly redundant, restating the defaults ('default distance...' then 'Defaults metric=distance, groupbyactivities=true'), but overall 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?

With no output schema, the description conveys the aggregate shape (totals grouped by activity type) but not the returned fields, and it omits the set of valid metric values. Adequate for a 4-param read tool but leaves gaps an agent calling it might hit.

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 coverage is 50% – metric and groupbyactivities lack schema descriptions. The description compensates for both by stating their defaults, which is useful. However, it never enumerates which metric values are valid (no enums exist), leaving a real gap for the metric 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 states a specific verb+resource: totals of one metric between two dates, grouped by activity type. An agent can grasp what it produces without opening the schema. It does not, however, name or distinguish itself from related aggregation siblings like get_stats or get_activities_by_date.

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?

There is no explicit when-to-use or when-not-to-use guidance and no mention of alternatives. The aggregation-over-a-range purpose is only implied, leaving the agent to infer selection against sibling summary tools on its own.

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