set_ability_cost

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

Annotations already declare readOnly=false, destructive=true, and idempotent=true, so the safety profile is covered. The description adds worth by naming the mutation target (the ability's CDO, i.e. the class default object rather than a live instance) and by describing the return struct, which exposes a match-validation signal (cost_effect_class_matches). It stops short of stating what happens to a previously assigned cost GE or whether the asset must be saved.

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 waste: the purpose sentence comes first and the return-shape sentence second. Every element earns its place, and the return struct is genuinely useful given there is no output schema.

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 inline return struct is exactly the right compensation, and annotations cover the mutation/safety profile. What is missing is operational context for a mutation on a blueprint CDO: whether the ability blueprint must exist or compile first, and whether the change needs a save/recompile to take effect. Otherwise the definition is complete.

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 asset-path parameters and the blueprint_name alias are already documented in the schema, including the alias-deprecation note. The description adds only the high-level meaning of the cost_effect_path (a GameplayEffect used as cost), which is a marginal gain over the schema. 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?

The description states a specific verb and resource ("Set the Cost GameplayEffect class on a GameplayAbility CDO") and the parenthetical explains exactly which GE this concerns, distinguishing it from the sibling set_ability_cooldown. An agent can tell what asset property is being mutated without opening the 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 explains what the tool does but gives no when-to-use guidance, no prerequisites, and never names an alternative or the conditions under which one would choose this over another ability-configuration tool. The closest sibling, set_ability_cooldown, is never mentioned, so routing is left entirely to inference.

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