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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true, while the description adds that changes are 'staged, never published.' It also discloses that disabling is a delete and is not exposed, which is useful mutation context beyond the annotations.

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 key constraints are front-loaded in a single efficient sentence, and the parenthetical packs important behavioral details. The trailing 'Tools revision' line is minor overhead rather than essential invocation guidance.

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?

The output schema and annotations cover return values and safety characteristics, and the description explains the staged/enable-only side effect. However, with two required parameters having no descriptions anywhere, the definition is not fully complete for correct invocation.

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% and neither required parameter is mentioned in the description. The agent gets no explanation of what 'container' or 'type' should contain, so the description does not compensate for the missing schema detail.

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: 'Enable a built-in variable,' scoped to the 'managed AdCopilot workspace.' It also distinguishes this from creating or listing variables by emphasizing built-in variables and enable-only behavior.

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 clearly states the usage boundary: 'enable-only: disabling is a delete and is intentionally not exposed.' This tells the agent not to use it for disabling, but it does not explicitly route to sibling tools such as gtm_list_built_in_variables or gtm_create_variable.

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