Add User Data Slot

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

With no annotations, the description carries the behavior burden. It discloses the mutation ('Add'), the return type (DescID as a nested list), and a concrete downstream use (path for get_params/set_params). It does not cover duplicate-slot or error behavior, but the core behavioral contract is stated.

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 definition is compact and front-loaded: action/target in the first sentence, return behavior in the second, dtype aliases in the third. The dtype list is slightly redundant with the schema enum, so it is not perfectly lean, but there is no filler or repetition of the title.

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, 3-required write tool with no annotations and no output schema, the description covers purpose, target class, return value, and integration path, while the schema covers parameter details. The main missing pieces are explicit sibling routing and error/duplicate behavior, which are not critical to a first correct call.

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 documents name, handle, dtype, min/max/step/value/default, including the vector/color [x,y,z] format. The description mostly restates the dtype enum, so it adds little parameter-level meaning beyond the schema baseline.

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 starts with a specific verb ('Add'), a specific object ('new User Data slot'), and scopes the target ('any BaseList2D'), which is enough to distinguish it from sibling list_user_data/remove_user_data even without naming them. The rigging/control-exposure context adds real-world purpose.

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?

It gives a clear use-case signal ('common rigging / control-exposure pattern') and explains the returned DescID can feed get_params/set_params, so an agent can infer when it is useful. However, it never explicitly says when to prefer this over list_user_data/remove_user_data, and there are no exclusion or alternative statements.

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