Create bones in world coordinates to rig Spine artwork without moving the art. Set parent, position, rotation, and length per bone.
Add bones in WORLD coordinates (y up). Each item: {"name", "parent" (default "root"), "x", "y", "rotation" (world degrees, default 0), "length" (default 0)}. Art never moves; only bones are added.
| Name | Required | Description | Default |
|---|---|---|---|
| bones | Yes | ||
| project | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and partially meets it: it discloses the coordinate space, per-item defaults (parent=root, rotation=0, length=0), and the key semantic that existing art is untouched. It omits any statement about permissions, failure behavior, or idempotency, so gaps remain for a mutation tool.
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?
Two tight sentences with the coordinate scope front-loaded and the item contract spelled out compactly. No filler, though the inline JSON-ish field list is dense and slightly cryptic without a described top-level parameter.
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?
No output schema exists, so the description need not explain returns, but for an unannotated mutation tool it should say more about the 'project' parameter and what happens to the existing rig state. The bone-item contract is complete, the surrounding context is not.
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 schema only declares an untyped array of free-form objects, so the description is doing real work: it enumerates the per-bone fields (name, parent, x, y, rotation, length) and their defaults. It does not explain the required 'project' parameter, which keeps it short of a 5.
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+resource ('Add bones') and pins down the coordinate convention (WORLD, y up), which is essential context for a rigging tool. It doesn't explicitly differentiate itself from nearby siblings like add_chain, but the purpose is unmistakable.
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?
There is no guidance on when to use this versus alternatives such as add_chain, reparent_slot, or the rig_* family. The 'Art never moves' note is a behavioral fact, not a use-condition, so the agent is left to infer when this tool is appropriate.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.