Check if separate 3D-printed parts physically assemble and hinged parts rotate using exact shared-material math and tolerance, not just a visual preview.
Prove that separate parts can PHYSICALLY assemble, and that a hinged part can turn — the ONE fit check, exact shared-material math, not a picture.
| Name | Required | Description | Default |
|---|---|---|---|
| joint | No | ||
| units | No | Default: "auto". | |
| recipe | No | ||
| part_paths | No | ||
| tolerance_mm | No | Default: 0.2. |
Changes observed during successful MCP inspections.
v1.5.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses that results come from exact shared-material math rather than rendering, which is genuinely useful behavioral context. It does not state whether the call is read-only, what it returns (pass/fail verdict vs. interference report), or the cost of running it, leaving significant gaps.
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?
A single front-loaded sentence with the core claim first. The rhetorical emphasis ('PHYSICALLY', 'ONE', 'not a picture') uses space but does real differentiation work, so little is wasted.
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?
Five parameters with two nested objects, no annotations, no output schema, and no documentation of the joint/recipe structures. The description never explains what a result looks like or which inputs are required for the assembly case versus the hinge case, which is inadequate at this complexity.
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 only 40%; only 'units' and 'tolerance_mm' are described in the schema. The description says nothing about 'joint', 'recipe', or 'part_paths' — including which of recipe vs. part_paths drives the check — so it does not compensate for the coverage gap.
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: proving that separate parts physically assemble and that a hinged part can rotate. The phrase 'the ONE fit check ... not a picture' distinguishes it from visual/screenshot-based verification siblings, though it does not name any specific sibling such as check_assembly_clearances or validate_assembly.
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 ONE fit check' implies this is the definitive check to run when physical assembly or hinge motion must be proven, and 'not a picture' implies it replaces a visual check. However, no sibling tool is named and no explicit when-not condition is given, so the agent must infer routing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.