animate_existing

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

With no annotations, the description must cover behavior fully. It discloses auto-mapping by name and ignored bones, but lacks details on side effects (e.g., file modification), permissions, error handling, or prerequisites for the skeleton file.

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 four sentences, each adding value: purpose, mapping logic, ignored bones, return format. It is front-loaded and concise with no redundant information.

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?

The tool has 3 parameters and no annotations. The description covers the skeleton mapping and return format, but leaves the animations array undefined, which is critical for usage. The presence of an output schema partially compensates for return value clarity.

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 0%, so the description must compensate. It clarifies skeleton_json_path as input skeleton and animations as what to add, but does not explain the structure of the animations array or the out_dir parameter. This is insufficient for a 3-parameter tool.

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 verb 'Add' and the resource 'EXISTING Spine 4.2 skeleton JSON', distinguishing it from siblings (describe_animation_type, import_psd_to_spine, list_animation_types) which cover description, import, and listing respectively.

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 implies usage when you have an existing skeleton and want procedural animations, and mentions that bones not following naming conventions are ignored, providing a context hint. However, it does not explicitly exclude alternatives or state when not to use.

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