Set customization

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

Annotations already declare this is a write operation in a closed system (readOnlyHint=false, openWorldHint=false), so the safety profile is covered. The description adds real value with the validation contract ('Unknown keys are rejected') and the key enumeration, but says nothing about persistence, whether changes apply immediately or need a restart, or whether values are type-checked per key.

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?

Two sentences, zero filler, and the enumeration of valid keys is front-loaded ahead of the rejection rule. Nothing needs trimming.

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 two-parameter mutation tool with no output schema and full schema coverage, the definition covers the essentials: what it writes, valid keys, and rejection behavior. What is missing is whether the change persists across sessions or requires a reload, and how it relates to the more specific sibling setters.

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 both parameters are already documented. The description's key list is slightly broader than the schema's examples (adds TriSpin, UIAnimSpeed, UIParticles, LowEnd), which is a marginal gain, but it adds no per-key value type or format semantics beyond 'New value'.

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 gives a specific verb ('Set') and a precise resource target ('any SaveData.Custom key'), so an agent can tell it is the mutating counterpart to reanim_get_customization and reanim_reset_customization. It stops short of explicitly naming those siblings or the namespace it writes to, but the operation itself is unambiguous.

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 when-to-use or when-not-to-use guidance, and no routing to alternatives. This matters because 'LowEnd' is listed as a valid key here while a dedicated sibling (reanim_set_low_end_mode) exists, and UI keys overlap with reanim_set_ui_theme — the description resolves neither overlap.

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