ga4_create_custom_dimension

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

With no annotations, the description carries the behavioral burden. It discloses the confirm guard ('must be true to actually create'), implies mutating action, and warns against duplicate predefined dimensions. It doesn't mention persistence/irreversibility, but the explicit confirm flag is a strong safety signal.

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 purpose and caveat are front-loaded, and the Args block is compact with no filler. Every sentence earns its place.

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?

It is well-scoped for a 6-parameter tool but not complete: the required display_name and the optional property_id/description remain unexplained, and it doesn't direct the agent to ga4_list_custom_dimensions as a precursor. Output schema and sibling names fill part of the gap, but not all.

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 0%, and the description compensates for parameter_name, scope (with an explicit enum), and confirm. However, it omits the required display_name as well as property_id and description, so an agent gets only partial parameter guidance.

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 ('Register') and resource ('custom dimension') and explains the outcome ('an event parameter becomes reportable'). It doesn't explicitly call out sibling alternatives like ga4_create_custom_metric or ga4_list_custom_dimensions, so it falls just short of full differentiation.

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?

It gives an explicit pre-check: verify predefined dimensions don't already cover the parameter, with the rationale that duplicating is wasteful. It doesn't say when to prefer the custom-metric sibling or archive/list tools, but the context is clear enough for a first-time caller.

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