animation.shape_key_add

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

Annotations already signal that this is a non-read-only, non-idempotent, non-destructive mutation (all hints false). The description adds only boilerplate risk/maturity and policy statements, disclosing nothing about side effects, duplicate-name behavior, transaction requirements, or what happens to existing shape keys. No contradiction with annotations, but the added behavioral context is minimal.

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 short and readable, with a reasonable structure (command identifier, then risk/maturity, then requirements). However, brevity here comes at the cost of substance — every sentence is present, but none of them communicate what the tool does or how to call it.

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 an 8-parameter mutation tool with a required keyName, a boolean fromMix, and an objectId targeting selector, the description is far too thin. An agent has no idea what operation occurs, what keyName should be, what fromMix controls, or how this differs from the sibling shape_key_keyframe tool. The presence of an output schema does not compensate for missing operation semantics.

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 only 38% (only _requestId, _authorization, _transactionId are documented). With coverage this low, the description must compensate, but it says nothing about keyName (required), fromMix, objectId, or name. The required keyName — the one parameter every caller must provide — has zero semantic explanation in either the schema or the description.

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 merely restates the command name (`animation.shape_key_add`) and labels it as a 'PartMe Blender Harness command' — a tautology that adds no functional meaning. It never states what the tool does (e.g., creates a shape key on a mesh/object) and does not differentiate it from nearby siblings like blender_animation_shape_key_keyframe.

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 invoke this tool versus alternatives such as shape_key_keyframe, insert_keyframe, or object-related creation tools. The only operational notes ('Risk: standard; maturity: L3' and 'Per-request argument checks and session policy still apply') are policy metadata, not usage direction or exclusions.

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