add_pin_joints

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

With no annotations, the description carries the full burden, and it does disclose real behavior: the tool opens an interactive 3D stage on success, attaches a browser stage link in some hosts, and auto-decimates oversized meshes for the stage. The tier note ('Requires Kiln Pro') hints at an authorization gate. What is missing is equally important for a geometry mutation tool: whether input meshes are modified in place or new files are written, and what happens on failure.

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 is correctly front-loaded, but the definition is then padded with a pricing pitch and upgrade URL that carry no tool-selection value. The inline-stage behavior is stated twice — once in the lead sentence and again in a dedicated all-caps paragraph — so the description spends its length on repetition and marketing rather than on the nine parameters.

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 must cover both semantics and return behavior. It does partially cover results by describing the interactive stage and the PNG preview fallback, which is helpful. It remains incomplete for a nine-parameter mutation tool: nothing about output file locations, whether existing geometry is altered, or error conditions.

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 78% across nine parameters, so the schema already documents defaults for scale, material, clearance_mm, pin_diameter_mm, application_class, design_id, and output_dir. The description adds no parameter-level meaning at all — notably nothing about how clearance_mm interacts with pin_diameter_mm or what application_class controls, which is exactly the kind of guidance a pin-joint tool needs. Baseline 3 is appropriate given the high schema 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 opening sentence names a concrete verb and resource: give two touching parts a pin-and-socket joint. That is far more specific than the name alone, and the requirement that parts be touching is a useful scoping fact. It does not, however, distinguish this from adjacent siblings such as get_joint_recommendation, recommend_joint_strategy, or add_assembly_interface, so an agent must infer when to create joints versus request a recommendation.

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 only usage condition offered is 'two touching parts,' which is a geometric precondition rather than guidance on when to select this tool. There is no mention of when not to use it, no named alternative from the many joint/assembly siblings, and no prerequisite steps such as having both parts loaded or validated.

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