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

Beyond the readOnly/idempotent annotations, the description discloses critical runtime behavior: only up to 20 km is examined, the response includes examinedMeters/truncated, a straight line is checked if geometry is incomplete, and the rate-limit implication is stated. This goes well beyond what annotations or schema convey.

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?

Although the description is several sentences long, every sentence earns its place: purpose, key limitation, accuracy caveat, longer-trip strategy, concrete call count, and a clear safety warning. It is front-loaded with the core function and uses formatting (IMPORTANT, TO COVER) to highlight critical sections without verbosity.

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 tool has no output schema, but the description compensates by revealing the response fields examinedMeters/truncated and by explaining how to cover a full trip. It also covers accuracy prerequisites, rate limits, and a safe reporting rule, making it fully actionable for an AI agent.

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 100%, so the baseline is 3. The description adds important semantics for the polyline parameter by explaining that a start/end-only input produces a straight-line check and that real route geometry is required for accurate results. Other parameters are already well described in the schema, so no further detail is needed.

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 opens with a specific verb+resource: 'report locations along that stretch of road with recent suspicious activity or stale scan coverage.' It clearly distinguishes this from sibling tools by emphasizing route-based analysis rather than point/regional lookups, and it immediately states the 20 km 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?

Provides explicit when-to-use and when-not-to-use guidance: 'this checks the road AHEAD, not a whole trip', warns against passing only start/end points, and prescribes the correct alternative for longer trips ('split the route geometry into consecutive 20 km segments and call this tool once per segment'). It also gives a safety rule: 'Do NOT report a route as clear unless you have covered all of it this way.'

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