Update an existing Google Tag Manager variable by its ID, applying new configuration settings to the specified container workspace.
Update an existing GTM variable by id.
| Name | Required | Description | Default |
|---|---|---|---|
| variable | Yes | ||
| account_id | Yes | ||
| variable_id | Yes | ||
| container_id | Yes | ||
| workspace_id | Yes | ||
| connection_id | No | ||
| session_token | No |
Changes observed during successful MCP inspections.
v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations are absent, so the description must disclose side effects and mutation behavior. It only says 'Update', omitting whether the object replaces or patches the variable, what happens on invalid ids, authorization requirements, or downstream 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 sentence is short and front-loaded with no fluff. However, for a seven-parameter mutation tool, one sentence without structured detail is under-sized and does not give the agent enough material to act on.
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?
With no annotations, no output schema, and a nested variable object, the description needs to explain scoping, required ids, and payload construction. It only says 'update by id', leaving critical invocation context missing.
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 none of the seven parameters are explained. 'by id' only weakly hints at variable_id, while required account_id, container_id, workspace_id, and the nested free-form 'variable' object remain completely unspecified.
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 ('Update'), a specific resource ('GTM variable'), and the selection criterion ('by id'). The word 'existing' also distinguishes it from creating a variable.
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 on when to use this tool versus gtm_create_variable or gtm_list_variables. No prerequisites, exclusions, or alternatives are mentioned; only the basic action is implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.