preview_material

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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuinely useful information not in structured fields: the return is MCP image content, which is essential since there is no output schema. It does not, however, explain the empty material_id default, what model/rotation defaults produce, or whether it re-renders live state.

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 no filler; the resource and the return format are stated up front. Nothing to trim.

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 simple read-only render tool whose annotations cover safety and whose return type the description actually discloses, this is close to adequate. The gap is parameter semantics and the inability to distinguish it from the several other preview/render siblings.

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% and all five parameters (model, width, height, rotation, material_id) are undocumented in both schema and description. The description's mention of a '3D PBR preview' weakly implies what model/rotation/width/height control, but it leaves material_id and the size defaults entirely unexplained.

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?

Names a specific action and outcome: returning a live 3D PBR preview as image content. The verb+resource is unambiguous, but it does not distinguish itself from siblings like render_node, preview_material_maps, save_material_preview, or preview_material_variations, which are all plausibly 'produce a visual' tools.

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?

There is no guidance on when to use this versus the many visual-output siblings, nor any prerequisite (e.g., whether a material must be loaded first). 'For visual inspection' is the only hint at context and it does not route the agent.

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