feature_chamfer

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

With no annotations at all, the description carries the full burden and does so: it names the failure modes (distance2/angle/flip with a mismatched mode, missing distance2 -> INVALID_PARAMS with nothing changed; a failed chamfer -> FUSION_API_ERROR, rolled back). It also discloses the result payload keys and that parent bodies appear in modified_bodies, so the agent knows the mutation's blast radius and its transaction semantics.

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?

Front-loaded with purpose, then modes, units, refs, errors, returns, and examples — a clean scannable structure. A couple of facts (units default mm, angle default 45) restate the schema and could be trimmed without loss.

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 an 8-parameter mutation tool with no annotations and no output schema, the definition supplies everything an agent needs: mode/parameter coupling, unit and expression conventions, where edge refs originate, error contracts with rollback behavior, and the return shape. Nothing material 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 coverage is 100%, so the baseline is 3, but the description adds cross-parameter meaning the schema cannot: which mode each of distance2/angle/flip belongs to, that flip swaps which face gets which value, that distances follow `units` and angles are in degrees, and that strings are Fusion expressions. It does not explain tangent_chain's effect or the interaction between flip and angle, which keeps it at 4.

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?

"Bevel edges of a body with a chamfer" gives a specific verb plus resource, and the mode enumeration (equal / two_distances / distance_angle) sharpens what kind of chamfer is produced. It does not address the closest potential confusion, however: the sibling timeline_edit_chamfer versus creating a new chamfer is left for the agent to infer.

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?

It gives concrete procedural context — edge refs come from inspect_query on the latest body and must be re-queried after later features — and ties each mode to the parameters it requires. It stops short of when-not guidance, e.g. creating a new chamfer versus editing one via timeline_edit_chamfer or choosing feature_fillet for rounding.

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