get_zones

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

With no annotations, the description carries the burden, and 'for reference only' is the only behavioral signal, implying a side-effect-free read. That is useful but thin: nothing about whether zones are user-configurable, whether they vary by sport, or whether the call can fail for profiles lacking zone data. The presence of an output schema relieves the description of explaining return values.

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 short sentences with no filler, and the core purpose is front-loaded. The second sentence adds non-redundant cross-referential context rather than restating the first.

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?

For a zero-parameter lookup with an output schema and no annotations, this is close to complete: purpose, read-only nature, and relevance to step heart-rate targets are all conveyed. A brief note on what the zone response covers (e.g., zone thresholds versus per-activity zones) would close the remaining gap.

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 tool takes zero parameters, so there is nothing to disambiguate and the baseline of 4 applies. The mention of 'hr' relates to workout step encoding rather than to any input, which is a helpful cross-reference but not strictly parameter semantics.

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 names a specific resource: heart-rate zones of the Final Surge profile. Combined with the tool name get_zones, the verb+resource pairing is unambiguous, and no sibling (list_workouts, get_parsing_rules, save_structured_workout, etc.) covers zones. It stops short of saying what a zone set contains (boundaries, sport, units), so it is clear but not fully specified.

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?

'For reference only' signals this is a lookup rather than a mutation, and the note that steps take heart rate in bpm ('hr') gives a concrete reason to call it when interpreting or authoring step targets. However, there is no explicit guidance on when to call this versus get_parsing_rules or get_examples, and no prerequisites or exclusions are stated.

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