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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds that the tool analyses the course only and lists explicit non-use cases, which provides context beyond the annotations. It doesn't discuss return format or limitations like rate limits, but the safety profile is well covered.

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 three sentences long, with the primary action front-loaded. Each sentence adds distinct value: the action, the use cases, and the exclusions. There is no redundant or filler text.

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 covers purpose, usage, and scope exclusions clearly. However, it does not explain the 'event' parameter or the expected return output. Since there is no output schema, a brief note on output could improve completeness, but the description is sufficient for correct tool selection.

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 itself describes gpx_xml and gpx_base64 with size limits and mutual exclusivity, covering 67% of parameters. However, the 'event' object has no description in the schema, and the tool description does not compensate for this gap. The main payload (GPX) is well-specified, but the optional event metadata lacks semantic guidance.

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 tool's function with a specific verb and resource ('Analyse a cycling-event GPX'), and explicitly differentiates it from the sibling tool by focusing on route demand analysis rather than fuelling. The exclusions (no athlete inspection, training prescription, etc.) further sharpen the scope.

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 provides explicit when-to-use guidance ('Use this when a rider, coach or agent asks what a route will demand, which climbs or sections matter...') and clear exclusions ('it does not inspect an athlete, prescribe training, predict a result, diagnose a medical issue, or analyse a completed FIT activity'). This is exemplary usage guidance.

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