GTM: Enable built-in variables

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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds nothing beyond the title: it does not say whether the call is idempotent, what happens to already-enabled variables, or that changes stay confined to the workspace until published — the behavior an agent most needs to know.

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?

One short sentence, front-loaded with the verb and resource, with the example clause placed where it helps. Nothing is padded, though the sentence carries almost no information beyond the tool name.

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?

There is no output schema, so the description could reasonably say what a successful enable returns or whether it is a no-op on already-enabled types. For a straightforward four-required-param mutation with full schema coverage, this is adequate but leaves the agent guessing about post-call workflow.

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%, so accountId, containerId, workspaceId and types are all documented. The example array in the description reinforces the expected camelCase value format but adds no syntax or constraint beyond the schema's 'BuiltInVariable types (camelCase from the GTM API)' note.

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?

States a specific verb and resource ('Enables built-in variables in the workspace') and even illustrates the value domain with example types. It is clear what the tool does, but it never distinguishes itself from siblings like gtm_save_entity or gtm_create_workspace that also mutate workspace state.

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 when-to-use guidance, no prerequisites (workspace must already exist, caller needs edit rights), and no mention of the follow-up step (creating/publishing a version) needed for the change to take effect. The agent must infer all operational context from sibling names.

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