material_set_subroutine

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

Annotations already indicate this is a non-read-only but non-destructive mutation with openWorldHint=false. The description adds little beyond that: it does not describe permissions, side effects, reversibility, or rate limits, and its return-value note is redundant because an output schema exists.

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 front-loaded and the slot list earns its place given the undocumented schema. The final sentence about return values is somewhat redundant because an output schema is present, but overall the structure is efficient.

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?

The description covers the slot parameter well and gives useful examples for shader, and the output schema can carry return details. However, it leaves the 'name' parameter unexplained and gives no sibling routing, which are meaningful gaps for a mutation tool with three required parameters.

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. It does so partially by listing valid slot names and giving slot/shader examples, but it never explains the 'name' parameter and does not exhaustively define valid shader values for each slot.

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 description states a specific verb and resource: 'Set the shader of a material slot,' with examples that clarify the operation. It is clear what the tool does, but it does not distinguish this from sibling tools such as material_set_field, material_set_texture, or material_set_cutout.

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?

No when-to-use, when-not-to-use, or alternative-tool guidance is provided. The examples illustrate parameter values rather than selection between this tool and closely related siblings.

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