assembly_create_joint

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

With no annotations, the description carries the full burden and does well: it discloses root-component placement, that geometry_one's part moves, the failure behavior ('Nothing is left on failure'), and the INVALID_PARAMS case for ambiguous native refs. It does not discuss permissions or broader destructive impact, keeping it below a 5.

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 description is long but front-loaded with the core purpose and then organized into refs, motion keys, return shape, and an example. For an 8-parameter joint creation tool, the detail is largely justified, though it is dense enough that some tightening could improve scanability.

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?

There is no output schema and no annotations, so the description needs to carry return and failure behavior, which it does by documenting the returned joint object and failure cleanup. It also covers reference formats, ambiguous reference errors, and per-type motion requirements, making it complete for correct invocation.

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?

Although schema description coverage is already 100%, the description adds substantial meaning beyond the schema: it defines the motion keys and defaults for each joint type, explains axis semantics, and clarifies that geometry_one is the moving snap while geometry_two is the target. The worked example further anchors expected parameter usage.

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 states a specific verb and resource: create a joint joining two parts, with the important scope note that it is created in the root component. It also clarifies which side moves, distinguishing the join semantics clearly enough for an agent to understand the operation.

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 clear context for using the tool and explains how to obtain valid references via inspect_query. It does not explicitly compare against sibling tools such as assembly_create_as_built_joint or assembly_create_joint_origin, so it lacks full alternative routing guidance.

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