list_activities

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is known. The description adds no behavioral context beyond that—no mention of pagination behavior, timezone conventions, or result interpretation. It merely repeats the date-range concept already present in the schema.

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 a single sentence with no filler, and the main action is front-loaded. It loses a point because it is so terse that it omits useful context, but from a conciseness standpoint it is 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 4 parameters, an output schema, and 25 sibling tools, a one-line description is under-specified. It doesn't clarify what categories of activities are included, how this relates to list_planned_activities, or any edge cases. The output schema addresses return values, but the tool still needs more context for correct selection and invocation.

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 descriptions cover 100% of parameters with formats, defaults, and examples, so the description carries no extra burden. The phrase 'date range' adds no new meaning beyond what start_day and end_day already communicate. Baseline 3 is appropriate since the schema does the heavy lifting.

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 'list' and the resource 'Coros activities' with a date range scope. It distinguishes from other list_* siblings like list_exercises, though it could be more explicit that these are completed activity records as opposed to planned activities.

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?

No guidance is provided on when to use this tool versus alternatives. Given the large number of sibling tools, including list_planned_activities and list_exercises, the description offers no exclusions or preferred context, leaving the agent to guess which list tool to invoke.

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