Measure an angle

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

Annotations already provide readOnlyHint=true, so the description need not re-disclose safety. The description adds useful behavioral detail: it returns degrees and operates on WORL-frame coordinates. Beyond that, it does not describe side effects, errors, or edge cases, but those are not critical given the read-only hint.

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?

One tightly packed sentence with no wasted words. The critical semantic information is front-loaded and the endpoint/kind/units are efficiently included.

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 two-parameter, read-only measurement tool with no output schema, this description is complete: it explains the input frame, point ordering, the specific angle definition, the endpoint/kind, and the return units. An agent has enough information to call the tool correctly without additional context.

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 input schema gives zero property descriptions, so the description must carry the semantic load. It meaningfully explains points_world: three worl-frame points, with the second point as the angle vertex. That is essential to using the tool correctly. scan_id is left implicit, but its meaning is standard for scene tools and inferable from the parameter name.

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 exact operation (measure an angle), the resource and semantics (three WORL-frame points), and how the angle is defined (vertex = second point). It also differentiates from the sibling scene_measure_distance by specifying kind=angle and returning degrees.

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?

The context is clear: an agent should invoke this when it needs the angle formed by three world-frame points, with the vertex at the second point. It does not explicitly name alternatives or give when-not-to-use guidance, but the angle/distance split with sibling scene_measure_distance is obvious from the description.

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