Measure Angle

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds only the default-selection behavior (first face), which is mostly a parameter detail; it says nothing about units, precision, or what happens with invalid face indices.

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?

A single front-loaded sentence with the core action first and the selection/default rule in a compact parenthetical. No waste, nothing to trim.

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 should say something about the return value — at minimum the unit (degrees vs radians) or format — and it does not. For a measurement tool that omission is a real gap, though the input contract itself is fully specified.

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 all four parameters are already documented in the schema, including defaults of 0. The description's 'defaults to each body's first face' merely restates the schema default, adding no new syntax or constraint information.

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 verb and resource ('Measure the angle') plus the precise scope: one face of each of two bodies, selected by index. That is enough to separate it functionally from siblings like measure_distance and get_bounding_box, though it never names an alternative 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?

The description implies when to use it (you need an angular measurement between two bodies' faces) and explains the default face selection, but offers no explicit when-to-use vs measure_distance or when-not-to-use guidance. Adequate but leaves routing to inference.

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