get_activity_fit_data

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

With no annotations provided, the description carries the full burden of transparency. It discloses a side effect—'Warning: adds significant data volume for long rides'—and hardware dependencies that affect success. It does not explicitly state that the operation is read-only or non-destructive, but given the lack of annotations and the 'download and parse' wording, this is a reasonable transparency level.

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?

Despite being lengthy, the description is well-organized with bullet points and sections (shift quality, notes, args). It packs substantive information without redundancy or filler. Each sentence contributes to understanding the tool's capabilities, prerequisites, or parameters, making the length appropriate for the complexity of the data returned.

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?

The description is comprehensive for an agent: it details the output categories (DI2 events, cycling dynamics, climb detection, etc.), defines shift quality terms, lists hardware requirements, and explains arguments. No output schema is provided, but the enumerated data types give sufficient context for expected results. The inclusion of a dedicated note about include_records ensures the agent understands the trade-off. Overall, nothing essential is missing.

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 descriptions for its properties, so the description fully compensates. It explicitly explains activity_id as 'Garmin activity ID' and include_records as 'Include full per-second time series (default False)' with a data volume warning. This covers both parameters completely, leaving no ambiguity about their meanings or defaults.

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 begins with a clear verb+resource: 'Download and parse FIT file for an activity to expose advanced cycling data.' It distinguishes itself from the standard REST API by stating it returns data 'not available through the standard REST API,' and enumerates specific advanced metrics such as DI2 shifting, cycling dynamics, and power curves. This makes the tool's unique purpose obvious relative to the many sibling tools.

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 provides useful usage guidance by noting hardware prerequisites ('DI2 data requires Shimano Di2 / SRAM eTap') and a warning about include_records adding significant data volume. It also states that it returns data not available through the standard REST API, which tells the agent when to prefer this tool. However, it does not explicitly name alternative sibling tools or give conditional 'use this vs. that' instructions, so it falls short of fully explicit when/when-not guidance.

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