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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description usefully adds the temporal trait that data is live/in-the-moment, but says nothing about refresh cadence, caching, rate limits, or the fact that an API key is needed — context that would matter for a live polling endpoint.

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?

Two sentences, no filler, with the live-position payload front-loaded and the authority claim last. Every clause carries information.

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?

With no output schema, the description compensates well by listing the returned fields (position, bearing, speed, route, trip, schedule deviation). Gaps remain around result volume/pagination behavior and freshness semantics, but nothing needed to invoke 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 description coverage is 100%, so limit, routes, and _apiKey are fully documented in the schema and the baseline of 3 applies. The description mentions route and trip only as returned fields, not as filter semantics, so it adds no meaning beyond the schema.

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 names the specific resource and enumerates exactly what is returned — position, bearing, speed, route, trip, and schedule deviation — which is far more than a restatement of the title. It is distinguishable in substance from stop-based siblings like trimet_arrivals, though it never names those siblings explicitly.

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?

'AUTHORITATIVE for live Portland fleet position and on-time performance in the moment' implies when to reach for it, but there is no explicit when-not guidance and no reference to trimet_arrivals, trimet_stops_near, or trimet_alerts, which an agent would need to route correctly among overlapping TriMet tools.

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