set_collection_param_default

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

Annotations already flag the non-read-only, idempotent, destructive nature, but the description adds real context: the asset is saved (persistence), the parameter must already exist, and it errors when the name is absent or the required value is missing. It does not spell out what the destructive hint actually overwrites (the prior default).

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?

Front-loaded with the action and scope, then the return shape. Two purpose sentences plus a returns block are all relevant; the returns block is verbose but justified since no output schema exists.

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?

No output schema exists, so the description compensates by enumerating return fields (default_set, saved, default_value, etc.). Combined with the error conditions and scalar/vector distinction, an agent has enough to call and interpret the tool.

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 coverage is 100%, so the baseline is 3, but the description adds the conditional mapping the schema does not state as a whole: a scalar parameter takes scalar_value and a vector parameter takes vector [r, g, b, a]. That ties param_type to the correct value field, which is meaningful selection guidance.

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 (Set) and resource (the default of an existing scalar/vector parameter of a Material Parameter Collection asset), plus the side effect of saving. An agent can distinguish it from sibling add_collection_scalar_param / remove_collection_param / clear_collection_params without opening schemas.

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?

The word 'existing' implies this is not the tool for adding parameters, and the error clause tells the agent it needs the right value field. However, no alternatives are named explicitly and there is no explicit when/when-not against the sibling add_*, rename_*, or clear_* tools.

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