add_part

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

No annotations are provided, so the description carries the full burden. It discloses accepted input shapes and the mate-vs-raw-placement relationship, but says nothing about side effects: whether the assembly must be active/open, whether external files are loaded, or what happens on a failed link. It adds format behavior but not mutation/effect transparency.

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 purpose statement is front-loaded and the remaining lines are laid out as compact format definitions with no filler. It is dense but every sentence, including the publish_interface cross-reference, 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?

For a 5-param nested tool with no output schema and no annotations, the description supplies the input-format knowledge an agent needs for the two hard composite parameters. What is missing is side-effect/permission context and the meaning of `assembly`, but the core calling information is present.

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% and nested objects are present, yet the description documents three of the five parameters in detail (source variants, placement forms, mate keys), which is meaningful compensation. `assembly` and `name` (defaults to 'Part') remain undocumented, keeping it short of a 5.

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 line states a specific verb and resource ('Add a part to an assembly') and names the mechanism (App::Link), which separates it from generic add_primitive/merge_assembly. It does not explicitly contrast itself against those siblings, but the purpose is unambiguous.

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 genuine usage guidance for `mate` ('place by aligning this part's published interface frame ... instead of (or after) a raw placement'), which is a real conditional. However it never states when to choose add_part over merge_assembly, copy_shape, or add_primitive, so the routing guidance is only partial.

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