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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds domain context about live or historical traffic flow and speed, but it does not explain return behavior, freshness guarantees, authentication needs, or how the temporal distinction actually works.

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 a single front-loaded sentence with no wasted words. It efficiently states the resource and the kind of 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?

For a zero-parameter read-only sensor tool, the description gives the essentials. However, the phrase 'now, or at a past moment' is ambiguous because no parameter allows selecting a past moment, and the sibling cell_sensor_roads_fi_at is not mentioned or ruled out, leaving a meaningful gap in temporal routing.

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 tool has zero parameters, so there are no parameter semantics for the description to clarify. The baseline for a parameterless tool is a 4, and the description does not introduce any misleading parameter expectations.

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 a specific resource (traffic counting stations on Finnish roads) and the data provided (flow and speed). It is clear enough to distinguish from unrelated siblings such as trains or wildfires, but it does not explicitly differentiate itself from cell_sensor_roads_fi_at, the obvious temporal sibling.

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?

There is no explicit guidance on when to use this tool versus alternatives. The phrase 'now, or at a past moment' hints at temporal usage, but it does not tell the agent when to choose this tool over cell_sensor_roads_fi_at or how a past moment would be requested with zero parameters.

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