merge_stl

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains the merging behavior, optional translation, return value shape, and a notable side effect: opening an interactive 3D stage and decimating oversized meshes for display. It stops short of describing error cases or file overwrite behavior, but the disclosed details are substantial and useful.

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 well-organized with a summary line, usage guidance, parameter documentation, return type, and side-effect note. A little redundancy exists ("Combines triangle data" and "Optionally translates each part" restate earlier points), but overall every section 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?

Given there is no output schema, the description appropriately includes the return dictionary fields. It also covers the inline 3D stage side effect and distinguishes the tool from its closest sibling. It could be more complete by specifying coordinate units or behavior when positions are omitted, but it is sufficiently complete for an agent to invoke the tool correctly.

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?

The input schema only provides parameter names, types, and a default, with 0% schema coverage. The description compensates fully by explaining `file_paths` as a JSON array of STL paths, `output_path` as the write target, and `positions` as an optional JSON array of {"x","y","z"} offsets per file. This adds meaningful semantic detail beyond the schema.

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 clearly states the tool's function: "Merge multiple STL files into a single mesh (supports positional offsets)." It uses a specific verb and resource, and explicitly differentiates itself from the sibling tool `merge_mesh_files` by noting the positioning capability.

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 direct usage guidance: "Use this when you need to position parts relative to each other" and "For simple concatenation without positioning, `merge_mesh_files` also works." This explicitly names an alternative and clarifies when each tool is appropriate.

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