Get Garmin activity supplementary data

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is known. The description adds valuable behavior: 'Unavailable sources are null with safe errors' and the constraint that the ID must be positive. No contradiction with annotations.

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?

A single, front-loaded sentence with no redundancy. It lists the data types compactly and states the null/error behavior without filler. Every element earns its place.

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 the simple input (one integer, no nested objects) and that an output schema exists, the description covers the key aspects: what data is returned, null handling for unavailable sources, and the positivity constraint. It doesn't mention when to use alternatives, but that's covered under usage guidelines.

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 schema has zero description coverage for activity_id, so the description must compensate. It adds that the ID must be 'positive' and that it refers to a single activity, which goes beyond the bare integer type and is useful for correct invocation.

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 uses a specific verb 'get', names the resource 'cross-sport supplementary Garmin China data', and enumerates the exact data types (canonical summary, laps/splits, etc.). The term 'supplementary' differentiates it from the sibling get_activity_details, making its purpose unequivocal.

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 implies this is for supplementary data via the word 'supplementary' but does not explicitly state when to use this tool versus siblings or when not to. No alternatives are named, leaving the routing partly to inference.

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