icu_update_custom_item

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

The description adds behavioral info beyond annotations: 'Only fields you pass are sent — others are left unchanged.' It also references external schemas for content. No contradiction with annotations (idempotentHint=true aligns with partial updates).

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 description is concise (few sentences), front-loaded with the main purpose, and every sentence adds value. No redundancy.

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?

Given 7 parameters, nested objects, and an output schema, the description covers core behavior (partial update, prerequisite, content reference). It does not explain return values, but output schema covers that.

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 description adds value by explaining partial update semantics and directing to external schemas for content. This compensates well beyond the schema alone.

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 clearly states the action ('Modify an existing custom chart/field/zones/panel') and resource, distinguishing it from siblings like icu_create_custom_item and icu_get_custom_items.

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 explicitly states when to use ('when the user wants to change one of their existing customizations') and suggests a prerequisite (icu_get_custom_items first). It lacks an explicit 'when not to use' clause, but the context is clear.

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