add_smart_object_definition_default_behavior

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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive, closed-world mutation, so the safety profile is covered. The description adds genuine extra context by disclosing that the private DefaultBehaviorDefinitions array is written via FArrayProperty reflection, plus the return shape (notably saved: bool, implying persistence). It stops short of stating permissions needed or whether it overwrites on repeat calls.

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?

Front-loaded with the action and target, followed by the reflection detail and a compact return summary. Two sentences with no filler, though the return object could be trimmed since it partly restates the parameters.

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 mutation tool with annotations and no output schema, the description carries the key behavioral disclosure (reflection into a private array) and describes the return shape, which the missing output schema would otherwise hide. Only the absence of permission/persistence conditions keeps it from being fully complete.

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 both parameters are already documented (behavior_class derivation rules, definition_path target). The description adds only the semantic framing that the behavior is definition-level and occupies the fallback role for slots without their own, which is marginal beyond the schema. Baseline 3 is appropriate.

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 (Attach) and resource (a definition-level default behavior on a USmartObjectDefinition), and clarifies the scope semantics ('applied to slots without their own'), which distinguishes it from the slot-level sibling add_smart_object_slot_behavior_definition. An agent can select it without opening the schema.

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 parenthetical 'applied to slots without their own' implies when this default is relevant versus a per-slot behavior, but no explicit when-to-use, prerequisites, or named alternative is given. Usage is inferable rather than stated.

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