sketch_extend

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

With no annotations, the description carries the behavioral burden and does well: it discloses that the curve may be replaced, that only one curve is affected per call, that callers should reuse refs from the result, and that points farther than 5 mm fail with INVALID_PARAMS. It also describes the return keys. It does not mention permissions, undoability, or behavior when no intersecting curve exists, so it is strong but not exhaustive.

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 front-loaded with the core action, then adds key constraints, return structure, and a compact example. Every sentence contributes useful information, and there is no filler.

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?

Although there is no output schema and no annotations, the description supplies the return structure, mutation/replacement behavior, failure condition, and an example call. It is largely complete for correct invocation, but it could mention behavior when no intersect is found or how it relates to adjacent sketch-editing tools.

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 the schema already defines all parameters; the baseline would be 3. The description adds operational meaning beyond the schema by clarifying that `point` must be within 5 mm or the tool fails with INVALID_PARAMS, that only one curve is extended per call, and that the returned refs should be used because the curve may be replaced.

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 states a specific verb and resource: extend the end of a sketch curve nearest `point` to the next intersecting curve. It also scopes the operation to one curve per call. However, it does not explicitly distinguish this from related siblings such as `sketch_trim` or `surface_extend`, so it stops short of a 5.

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 intended use is implied by the description: extend a sketch curve's end to the next intersection, with a 5 mm proximity tolerance. It gives a failure condition for points farther than 5 mm, but it does not say when to use this versus alternatives like `sketch_trim` or `surface_extend`.

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