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

Annotations only declare the generic write-capable profile (readOnlyHint=false, destructiveHint=false), so the description carries the real burden – and it does: it discloses the connection prerequisite, that attaching is equivalent to an upload and becomes visible via get_event_course, and that an existing GPX is only overwritten under an explicit replace flag plus athlete consent. That is exactly the kind of side-effect and safeguard context annotations cannot express.

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?

Four dense sentences with no filler, front-loaded with the resource and then the two mode conditions. The final consent/replace sentence is long but is a genuine safety instruction, not padding; the enumeration of returned fields (id, name, km, climbing, last edited) earns its place since there is no output schema.

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-required-param, dual-mode tool with no output schema, the description covers prerequisites, mode selection, side effects, and safety constraints, and explicitly documents the list-mode return fields. Nothing an agent needs to call it correctly 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?

Schema coverage is only 25% (just 'query'), so the description must compensate, and it does for three of four params: routeId as the route selector that also switches modes, eventId as sourced from list_events, and replace as the overwrite gate. It adds nothing about the query name filter beyond the schema's own 'part of a route name', leaving a small gap, but overall the semantics are strong.

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?

States a specific resource (the athlete's saved Ride with GPS routes) and cleanly splits the tool into its two real behaviors: listing when routeId is absent, and attaching a course when routeId + eventId are given. An agent can tell it apart from get_event_course and list_events, which are named as the counterpart 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?

Gives explicit mode-selection rules keyed on parameters ('Without routeId: lists them', 'With routeId + eventId (from list_events): puts that route on the event'), names the prerequisite (athlete must have connected Ride with GPS in Connections), and adds a when-not constraint ('Attach only the route the athlete picked; an event that already has a GPX is replaced only with replace:true after they agree').

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