create_custom_dimension

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

No annotations are provided, so the description must bear the full transparency burden. It discloses validation rules (scope values, display_name charset) but not return behavior, idempotency, or propagation delays. The verb 'Create' makes the mutating nature obvious, avoiding contradiction.

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 concise sentences, front-loaded with the action, every clause adds operational detail. No redundant filler or unnecessary commentary.

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 5-parameter create operation with no annotations or output schema, the description is too thin. It fails to explain the required property_id, return/response behavior, or how the created dimension appears in list_custom_dimensions. This leaves the agent to infer important invocation details.

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 has 0% description coverage, so the description must compensate. It explains parameter_name and scope values, and display_name constraints, but omits property_id (a required parameter) and description. This is useful but incomplete.

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?

Description uses specific action 'Create' and resource 'custom dimension', making it clear it creates a GA4 custom dimension. It also distinguishes from siblings like list_custom_dimensions, archive_custom_dimension, and create_custom_metric.

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?

No guidance is given on when to use this tool versus alternatives such as create_custom_metric, or how it relates to archive_custom_dimension. No prerequisites or decision context are provided beyond the action itself.

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