set_fill_resource

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

There are no annotations, so the description carries the full behavioral burden. It discloses the mask-Fill channel exception, but it does not say whether an existing resource is overwritten, what permissions or preconditions apply, or how material_mode changes behavior.

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 two short sentences with no wasted language, and the core purpose is front-loaded before the mask-Fill caveat.

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 mutation tool with four parameters, no annotations, and no parameter descriptions in the schema, the description is too sparse. The output schema exists so return values need not be explained, but key invocation details around material_mode, uid, and resource_url remain missing.

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 explain the four parameters. It clarifies channel behavior for mask Fills but does not define uid, resource_url, or material_mode, and the phrase 'whole material' does not explicitly map to the material_mode boolean.

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 gives a specific verb, 'Assign', and a specific resource, a Painter resource, to Fill targets: a channel, a whole material, or a mask Fill. It is clear what the tool does, though it does not explicitly distinguish itself from close siblings such as set_fill_channels or set_fill_base_color.

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?

It gives one useful conditional: omit channel for a Fill inside a mask because such a Fill has no channels. However, it does not explain when to set material_mode, nor does it compare this operation with sibling tools that also modify Fill settings.

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