list_gtm_variables

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

Annotations declare readOnlyHint=true and destructiveHint=false, so the tool is safe and non-destructive. The description adds behavioral context by detailing data sources (live container vs workspace) and explaining why variables matter for triggers. It does not contradict 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 description is four sentences long, each serving a purpose: stating the action, explaining sources, and providing motivation. There is no fluff, and it is front-loaded with the main purpose.

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?

Given the presence of an output schema, the description does not need to cover return values. However, it lacks parameter explanation and usage examples. The explanation of variable sources is good, but the overall completeness is adequate but not excellent.

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?

The input schema has two parameters (gtm_account_id, gtm_container_id) with 0% schema description coverage. The description does not mention these parameters or explain their purpose/format. Without this, the agent must infer from context, which adds ambiguity.

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 clearly states it lists GTM variables, distinguishing between custom and enabled built-in variables. It explains the sources (live container for custom, workspace's enabled-built-ins list for built-in). This definitively sets it apart from sibling tools like list_gtm_tags or list_gtm_triggers.

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 implies when to use the tool (to list variables for trigger reference) but does not explicitly state when not to use it or provide alternatives. Siblings exist such as get_gtm_trigger or list_gtm_tags, but no guidance is given on selecting between them.

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