get_data_layer_instances

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

Annotations already declare readOnly/idempotent/non-destructive/openWorldHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: it states the underlying engine call (UDataLayerManager::ForEachDataLayerInstance) and, more importantly, that an empty result on a non-WP default map is expected rather than an error.

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 verb+resource in the first sentence, then the implementation note, then the empty-result caveat, then the return shape. The engine class reference is a bit jargon-heavy but is a deliberate verification signal in this toolset; no sentence is redundant.

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 no output schema, the description usefully enumerates the return shape (world_name, is_world_partition_enabled, data_layer_instances fields, count, note), which is what an agent needs to consume the result. Minor gaps remain: it does not say whether streaming-level or runtime state is reflected, or whether PIE is required.

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?

The tool takes zero parameters, so the baseline is 4. There is nothing for the description to clarify beyond the empty input object already in the 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?

States a specific verb and resource ('Lists the editor world's data layer instances') with an explicit scope modifier ('editor world's'), which separates it from asset-side siblings such as get_data_layer_assets and from actor-side tools like list_world_partition_actors. It does not name a sibling directly, so it stops just short of a 5.

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 explicit when-to-use vs. when-not or named alternative. The one piece of usage guidance is interpretive: an empty list on a non-WP map is the correct result, which steers the agent away from treating emptiness as failure, but general selection guidance is only implied.

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