Add Sketch External

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

Beyond the readOnly/destructive annotations, the description discloses a non-obvious behavior: the projected element gets a negative geom index so subsequent constraints can reference it. It also clarifies that the result is construction geometry anchored to upstream geometry, which is exactly the kind of behavioral context annotations do not provide.

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 dense and front-loaded: a one-line definition, a compact grammar for ref, a behavior note about negative geometry indices, and a motivating use case. Every sentence contributes information, and there is no filler or repetition of schema fields.

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 tool with a nested object and no output schema, the description covers the essential input grammar, the result behavior, and why the user would want this. It omits prerequisites such as whether the sketch must be open, but the core invocation information is present and usable.

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?

With 0% schema description coverage, the description compensates well by detailing the ref parameter syntax: {handle, edge: tag|'EdgeN'}, the face/vertex variant, and {handle, tag} with e_/f_ prefixes. The sketch parameter is not described, but its name is self-explanatory, and the difficult parameter is covered thoroughly.

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 begins with a specific verb and resource: 'Project an external edge/face/vertex into a sketch as construction geometry.' This clearly distinguishes the tool from siblings like add_sketch_geometry and add_sketch_constraint, and the phrase 'construction geometry' adds precise 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?

The description gives an explicit use case: 'Use this to make a sketch that stays anchored to upstream geometry' with a concrete example of a hole 5mm from a tagged edge surviving pad-length edits. It does not name alternatives or state when not to use it, but the intended context is clear.

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