get_activity_interval_stats

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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. It discloses that this is a read operation, performs no numeric calculations, preserves all upstream fields including nulls/zeroes/future fields, adds provenance and units, and explicitly flags that source completeness is unknown. This is far beyond the minimum and gives the agent accurate expectations.

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 dense but every sentence earns its place by adding a needed constraint, caveat, or semantic clarification. It front-loads the purpose, then provides usage context, then covers data-handling details. No filler or redundant restatement of the schema is present.

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 an output schema exists, the description does not need to explain return shapes, yet it still covers invocation context, range semantics, partial-data behavior, provenance, unit pitfalls, and a cross-reference to get_metric_definitions for conditional documentation. This is complete enough for an agent to invoke the tool correctly despite missing annotations.

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?

With 0% schema description coverage, the description must compensate, and it does: it explains that indices are sample indices, not seconds, and that the range is half-open. It also clarifies unit semantics for respiratory fields. It does not explicitly explain activity_id or api_key, but those are either obvious from the name or optional with a default, so the most error-prone parameters are well covered.

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 opens with a specific verb and resource: "Read upstream interval statistics for a half-open sample-index range." It clearly distinguishes this from sibling tools like get_activity_streams and get_activity_intervals by emphasizing the Interval object and sample-index semantics. No ambiguity remains about what the tool does.

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 tells the agent when to choose this tool: when the client needs the Intervals.icu Interval object for [start_index, end_index). It also names get_activity_streams as the alternative for mapping sample indices to elapsed time. It does not explicitly contrast with the closely named sibling get_activity_intervals, but the primary selection context is clear and actionable.

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