set_spawn_actor_class

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

No annotations are provided, so the description carries the full disclosure burden. It does explain the UE 5.6 object-defaults quirk and declares the return dict, which is genuinely useful. However, it does not state side effects (e.g., whether the containing Blueprint is recompiled, whether prior pin values are overwritten, or how failures like a missing node are surfaced). For a mutating tool with zero annotation coverage, this is a moderate gap, though the core behavior is clearly disclosed.

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 efficient: a one-sentence purpose, a brief why-this-helper rationale, a compact Args/Returns block, a KB pointer, and a complete example. Nothing is redundant — the UE 5.6 note and the KB link earn their place as actionable guidance, and the overall length is appropriate for a tool with four 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?

With an output schema present, the return-value type is already machine-readable. The description covers the remaining essentials: purpose, the exact node type, the reason to prefer it over an alternative, all parameter meanings, a default, and a runnable example. There is no obvious missing information an agent would need to call it correctly.

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%, but the description's Args section documents every parameter: blueprint_name as "Asset name", node_id as "SpawnActor node GUID or node name", actor_class with an example value ("BP_Projectile_C"), and graph_name with its default ("EventGraph"). The example call even shows an asset path format ("/Game/MCP_Test/BP_Example"), so the description fully compensates for the empty schema.

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 opens with a direct, specific statement — "Set the Class pin on an existing SpawnActorFromClass node." — which names both the action (set pin) and the exact node type. It further disambiguates from nearby siblings by explicitly referencing add_blueprint_spawn_actor_node and set_node_pin_value, so an agent can tell this tool apart without opening any 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 description gives explicit when-to-use guidance: "use this helper after add_blueprint_spawn_actor_node instead of set_node_pin_value." This names the recommended preceding step and the alternative tool to avoid, which is exactly the kind of routing an agent needs to make the right choice among ~100 blueprint-node sibling tools.

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