Stage Material Set

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

With no annotations, the description carries the full behavioral burden and does so well: it discloses that the edit is undoable, saves like a hand edit, affects every mesh using the material including merged pieces, persists to edits.json, and emits material_change. Error cases and page reply fields are also named.

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 dense but front-loaded with the core action and mostly earns its length through behavioral and error details. It is somewhat run-on, but for a mutation tool with no annotations and no schema descriptions, the information density is appropriate.

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?

An output schema exists, so return values need not be explained, but the description goes further by naming reply fields and emitted events. It covers persistence, side effects, and failure modes; the main gap is the unexplained required scene parameter.

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 all four parameters. It adds useful semantics for color (linear RGB), material (exact name then case-insensitive fallback), and object (must have exactly one material), but it never explains the required scene 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?

The description uses a specific verb and resource: setting a material's base colour on the open page, with immediate scope ('now') and persistence semantics. It also distinguishes the material path from the object path, so an agent can tell what this tool does without opening the 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?

It clearly states the primary usage and gives an explicit alternative: use object= instead of material when the object has exactly one material. It also lists error conditions that constrain valid calls, though it does not explicitly route against sibling tools such as stage_object_set.

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