Apply theme preset

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

Annotations already declare readOnlyHint=false and openWorldHint=false, so the agent knows this is a closed-world mutation. The description adds real value by naming the mutated field (SaveData.Custom) and stating that a live snippet is returned despite there being no output schema, but it never says whether an existing customization is overwritten or how to undo the change.

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?

A single sentence with the verb and target front-loaded and no filler. It is appropriately sized, though 'live snippet' is unexplained jargon that slightly blunts the payoff of an otherwise tight 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 mutation tool with no output schema, the description covers the essentials (what it writes to, that it returns a snippet) and annotations cover the safety profile. It nevertheless omits whether existing theme state is replaced, whether a prior list call is required, and what the returned snippet is for.

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% and the single required parameter is already documented in the schema, including its provenance ('Preset name from reanim_list_theme_presets'). The description's phrase 'built-in theme preset' only mildly reinforces that constraint, so the baseline 3 is appropriate.

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 (apply) plus resource (built-in theme preset) and names the exact mutation target (SaveData.Custom), which separates it from read-side siblings like reanim_list_theme_presets and reanim_get_ui_theme. It doesn't explicitly contrast with the nearby write tools reanim_set_ui_theme or reanim_set_customization, so an agent still has to infer which write path applies.

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 gives no when-to-use guidance, no prerequisites, and no alternatives. The only routing hint ('Preset name from reanim_list_theme_presets') lives in the schema, not the description, and there is no mention of how this differs from reanim_set_customization or reanim_set_ui_theme.

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