get_ism_instance_info

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: it reads the editor-world component (no PIE required) and clarifies the two-mode contract. This is useful beyond the annotations, though it doesn't discuss failure/auth or performance characteristics.

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 core purpose and mode logic are front-loaded in the first two sentences, and the returns block is warranted because there is no output schema. There is mild redundancy ("Two modes from one call" restates the opening), but each part earns its place.

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 present, the description fully specifies the return shape for both modes (field names and types), which is exactly what an agent needs to consume the result. Combined with the mode logic and editor-world note, nothing essential 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 coverage is 100%, so the baseline is 3. The description goes further by tying instance_index to the mode switch and explaining that world_space controls the coordinate frame of the returned transform, adding semantics the schema descriptions only hint at.

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 specific verb+resource (count/read instances in an InstancedStaticMeshComponent) and immediately distinguishes the two operating modes. An agent can tell this apart from write-side siblings like add_ism_instance, clear_ism_instances, and update_ism_instance_transform without opening a 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?

It gives explicit mode-selection guidance: omit instance_index for COUNT mode, pass it for per-instance mode, and notes it reads the editor world so no PIE is needed. It does not name sibling read/write alternatives (e.g. add_ism_instance) for the case where the agent actually wants to modify instances, so differentiation from siblings is implied rather than stated.

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