set_state_theme_color

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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description goes well beyond them: it explains UUID preservation for existing names, fresh UUIDs for new colors, the caller's obligation to re-bind orphaned ColorRefs, and the TSet/ColorRef storage model that permits ambiguous duplicate names. This is exactly the behavioral detail an agent needs for a destructive mutation.

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?

Purpose is front-loaded before the CRITICAL behavior note, and the returns list closes it out cleanly. Slightly penalized for restating the r/g/b/a defaults that the schema already documents, a mildly redundant sentence.

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 destructive, 6-parameter mutation with no output schema, the description supplies the mutation semantics, the UUID/ColorRef consequences, caller responsibilities, and an explicit Returns field list (including was_new and saved). An agent has everything needed to call it correctly.

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?

With 100% schema coverage the baseline is 3, but the description adds real semantic weight: it ties color_name to case-insensitive DisplayName matching and explains that ColorRef (not display name) is the uniqueness key. It restates the r/g/b/a defaults already present in the schema, which is the only non-additive part.

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+resource ('Upsert a theme color in UStateTreeEditorData::Colors') and immediately distinguishes an upsert from a create via the CRITICAL note on existing DisplayName. An agent can tell this mutates StateTree theme colors without opening any 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?

The description conveys the upsert condition (same case-insensitive DisplayName preserves UUID) and a caution about duplicate names, which is implied usage guidance. However it never names an alternative (e.g. get_state_theme_colors) nor states explicit when-not-to-use conditions, leaving routing to inference.

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