select_faces_by_sides

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

With no annotations, the description carries the burden and does disclose a key behavioral trait: extend adds to the current selection instead of replacing it, and it reports how many faces were selected. It does not state mode/prerequisite requirements (e.g. edit mode, active object), which is a meaningful gap for a Blender selection tool.

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?

Two front-loaded sentences state purpose and motivation, then a compact Args block and a one-line return note. No filler, and the most decision-relevant content (ngon/triangle detection) comes first.

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 4-parameter selection tool with an output schema, the description covers purpose, all parameters, and selection semantics adequately. The only shortfall is not noting execution prerequisites (edit mode / active mesh), which matters 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?

Schema description coverage is 0%, so the description must compensate, and it largely does: it explains that number compares sides (faces have at least 3), lists the comparison enum semantics, and clarifies extend's add-vs-replace behavior. Only object_name is left largely self-evident; the rest add real meaning beyond the bare 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?

States a specific verb and resource ('Select faces by how many sides they have') and immediately names the concrete outcomes (ngons, triangles). An agent can distinguish this from sibling selectors such as select_by_index, select_by_axis, and select_similar without opening a schema.

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 direct way to find ngons (GREATER than 4) or triangles (EQUAL to 3), which is what topology cleanup usually needs' gives concrete when-to-use context and even maps comparison values to goals. It stops short of naming the sibling tools it replaces or stating exclusions, so it is clear but not fully routed.

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