motion_create_keyframe_curve

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

With no annotations, the description carries the full burden and does well: it discloses that a new curve is created from scratch with one keypoint, that it refuses certain inputs, and how `default` behaves. However, it does not explicitly state that this is a write operation that modifies the document, nor does it mention non-reversibility, so it's not a perfect 5.

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 long but well-organized and free of fluff. Every sentence adds value: purpose, grounding, constraints, and parameter detail flow logically. It earns a 4 rather than 5 because it could be slightly tighter, but it's still highly readable and efficient.

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 7-parameter tool with no annotations and zero schema coverage, the description covers the core functionality, target parameter type, and key constraints. It leaves out explicit explanations for `path`, `scenenode_id`, and `interpolation`, but the overall context and output schema mitigate those gaps. A 4 is appropriate.

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 0%, and the description compensates for key ambiguous parameters: it clarifies `parameter_path` (scalar channel, e.g., 'Style/Face/Color/Red' vs compound) and `default` (overrides rest value or reuses current value). Other parameters like `time_seconds`, `value`, and `interpolation` are not explicitly detailed, but their meaning is inferable from the context.

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 clearly states the action: 'Start animating a leaf parameter that has NEVER been keyframed in Motion — creates its curve from scratch, seeded with one keypoint.' It also distinguishes itself from the sibling tool motion_add_keyframe, which is for already-keyframed parameters.

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?

Explicitly specifies when to use this tool (only for never-keyframed leaf parameters) and when not (already keyframed → use motion_add_keyframe; group parameters → refused). It also gives precise targeting guidance by instructing to target scalar channels rather than compound properties.

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