Create Block From Entities

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

Beyond the mutation hint (readOnlyHint=false), the description discloses that originals remain in model space, that unresolved handles are surfaced in `skipped` rather than silently dropped, and that a fully-unresolved call fails instead of creating an empty definition. These side-effect and error-handling details materially shape agent expectations.

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?

Three sentences, front-loaded with the core purpose, and each subsequent sentence adds distinct information: non-consuming semantics, alternative tool routing, and error-handling behavior. No filler or restatement of the title.

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 an output schema, the description covers creation semantics, side effects on source entities, the placement workflow, and failure modes. The existing output schema handles return-value documentation, so nothing an agent needs to call this correctly 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 adds real value by explaining the behavior of the handles parameter (unresolved ones go to `skipped`, all-unresolved fails), which goes beyond the schema's bare 'List of entity handles to include in the block.' name, base_x, and base_y appropriately rely on the schema at full coverage.

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 first sentence states a specific verb+resource: 'Create a new block definition from existing entities in the drawing.' The scope is sharpened by distinguishing this from AutoCAD's BLOCK command (non-consuming) and from siblings like block_insert (placement) and block_explode, so an agent can tell them apart.

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 follow-up alternative: 'use `block_insert` to place copies, and delete the originals yourself if you want the command's behaviour.' It also notes cross-engine portability ('Works on both engines'), giving an agent clear context for when and how to chain this call.

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