create_mass_spawner_actor

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

Annotations cover safety (readOnlyHint false, destructiveHint false), but the description adds critical non-obvious behavior: the level is not saved, config_path is echoed but not linked, and duplicate labels silently resolve to the first match. These are real side-effect/disambiguation facts not present in annotations or schema.

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-loads the action, then the two gotchas (no save, no link), then the uniqueness warning, and closes with the return shape. Dense but every clause carries a warning the agent needs, with only mild redundancy in restating config_linked.

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 spawn/mutation tool with no output schema, the description supplies the return keys, the persistence caveat, the linking-is-separate caveat, and the label-matching pitfall. Nothing material for correct invocation is missing.

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 already 100%, so the schema documents location, actor_label, and config_path. The description reinforces the config_path semantics (echoed, not linked) and the zero-rotation default, which adds a little beyond the schema, but the baseline for full coverage is 3.

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 (Spawn) and resource (AMassSpawner actor) plus the exact placement (editor world at location, zero rotation) and that it labels the actor. It is unambiguous and clearly distinct from sibling spawn_actor or spawn_mass_entities.

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?

Explicitly names the alternative for the linking step (set_mass_spawner_entity_types), warns that config_path is only echoed and not linked, and notes that labels must be unique because the spawner tools take the first match. This is precisely the when/when-not guidance an agent needs.

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