preview_material_maps

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

Annotations already declare readOnly/idempotent/non-destructive safety, so the bar is lower. The description adds genuine lifecycle context beyond them: the temporary export is deleted once its bytes are embedded, making the ephemerality of the operation clear.

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 tight sentences, front-loaded with the core action, then the deletion caveat, then the alternative. No wasted words.

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?

Annotations cover the safety profile and there is no output schema, so return-value explanation is less critical. However, for a 3-parameter tool with 0% schema coverage, omitting any description of size, profile, or material_id leaves a real gap in how to call it 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?

Schema description coverage is 0%, so the description carries the full burden for size, profile, and material_id, yet it explains none of them. It obliquely implies format/profile context (PNG/JPEG/WebP) but adds no real semantics for any parameter.

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+resource+scope: 'Export and return all PNG/JPEG/WebP PBR maps as labeled MCP images.' It also names the sibling it is not (export_material), letting an agent distinguish it without opening either 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?

Gives an explicit routing rule: use this for in-context MCP images, use export_material when persistent output files are required. The when-to-use and the alternative with its selecting condition are both stated.

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