set_gameplay_effect_modifier_custom

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

Annotations already declare the safety profile (destructiveHint=true, idempotentHint=true), so the bar is lower, and the description usefully adds a return-shape block including the verification field calculation_class_matches and a set flag. However, given destructiveHint=true it never states what prior magnitude configuration is lost when switching to a custom calculation class, and no auth/save/compile requirements are mentioned.

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?

The operative sentence is front-loaded and compact, followed by an enumerable return block that earns its space because no output schema exists. Slightly verbose return listing, but nothing is wasted filler.

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, idempotent mutation with 7 fully-documented parameters and no output schema, the description covers the operation and compensates for the missing output schema with a return-value block. The residual gaps are non-blocking selection guidance rather than call-correctness information.

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% and every parameter (including the blueprint_name alias and the coefficient/pre/post multiply defaults) is documented in the schema itself. The description adds no syntax, format, or constraint detail beyond that, so the 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 names a specific verb ("Switch"), resource ("an existing GE modifier's magnitude"), and the target state (CustomCalculationClass), with a parenthetical explaining who computes it. That magnitude-mode name implicitly separates it from the many sibling magnitude setters (attribute_based, set_by_caller, attribute_curve, custom_curve), though it never names a sibling explicitly.

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, when-not-to-use, or alternative-selection guidance. An agent is told what the tool does but not why it would pick this over set_gameplay_effect_modifier_custom_curve or the other modifier setters, and no prerequisites (GE must exist, modifier index must be valid) are stated.

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