download_activity_tcx

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

There are no annotations, so the description carries the full burden of behavioral disclosure. It explicitly discloses the side effect of saving the file and the return behavior of providing a file path. It could add more detail about overwrite behavior or where the file is stored, but the core behavioral traits are clearly conveyed.

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?

Three short sentences, each earning its place: the action, the side effect/result, and the data content that helps with tool selection. It is front-loaded with the main purpose and contains no filler.

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 simple one-parameter download tool, the description is mostly complete: it identifies the target, explains the side effect, and notes what the file contains. An output schema exists to cover return-value structure, so the description need not elaborate further. Minor gaps like file naming or storage location are not critical for correct 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?

The schema provides no description for activity_id, so the description's mention of 'a specific activity' adds minimal context. While the parameter name is fairly self-explanatory, the description does not explain the expected ID format, how to obtain it, or any constraints. It is adequate but not enriching.

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 action (download), the resource (a TCX file for a specific activity), and the result (saves file, returns path). It distinguishes this tool from the many activity-read siblings and from the other download_activity_* tools by naming the TCX format and its contents.

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 when to use this tool by noting that TCX files contain GPS + heart rate + cadence data, which helps an agent choose between formats. However, it does not explicitly mention alternative download formats (FIT, GPX, KML, CSV) or state when one format should be preferred over another.

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