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

Annotations already indicate the operation is not read-only, is destructive, and is idempotent. The description adds little beyond "by resource name" and does not explain what makes the update destructive, what fields can change, or any permissions or side effects.

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 short and front-loaded with the core action. However, the trailing "Tools revision: 5c9bea8f." does not help an agent invoke the tool and the remaining text is too sparse to be useful.

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?

This is a destructive update tool with three parameters and no schema descriptions, so the description needs to do more work. An output schema exists, so return values need not be explained, but the description omits essential update behavior and parameter guidance.

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 0%, so the description must compensate for undocumented parameters. It only implies that `name` is a resource name; it does not explain `display_name` or the `update_mask` parameter, including its default value.

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: "Update a custom dimension." It is clear what the tool does, but it does not distinguish this from sibling tools such as ga4_update_custom_metric or ga4_create_custom_dimension.

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 gives no guidance about when to use this tool versus alternatives, nor does it mention prerequisites such as needing an existing dimension or a required resource name format. Usage must be inferred from the name alone.

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