add_collection_vector_param

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

Annotations cover the safety profile (not read-only, not destructive, not idempotent, not open-world), so the bar is lower. The description adds the return shape, including already_existed and saved flags, which hints at duplicate handling, but it does not state whether the change persists without an explicit save or what happens when the parameter already 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 action statement is front-loaded in a single clean sentence, and the returns block is compact. The returns enumeration is somewhat long, but it is not redundant filler.

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?

With no output schema, the description usefully supplies the return fields, and annotations cover mutation semantics. However, for a write tool it omits persistence requirements, error conditions (e.g., invalid collection_path), and the interaction with existing parameters beyond the already_existed flag.

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 100%, so the three parameters are already documented in the schema, including the [r, g, b, a] default format. The description adds nothing beyond 'vector RGBA,' so the baseline 3 applies.

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 and resource with the parameter type qualified: 'Append a vector RGBA parameter to a Material Parameter Collection.' This distinguishes it from the scalar variant by implication, but it never names a sibling tool the way a 5 would.

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 add_collection_scalar_param, remove_collection_param, or set_collection_param_default, and no prerequisites such as needing an existing MPC asset at collection_path. The agent must infer all of this from the name.

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