gtm_list_containersList all containers from a Google Tag Manager account, returning IDs, names, public IDs, and domains. Specify account ID to retrieve container data.
List all containers in a GTM account, with their IDs, names, public IDs, and domains.
| Name | Required | Description | Default |
|---|---|---|---|
| account_id | Yes | The GTM account ID | |
| page_token | No | Continuation token from a previous call to fetch the next page of results |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds scope ('all containers') and output fields, but it does not disclose that pagination may be required via page_token, despite 'all' implying a single complete response. This is a notable behavioral gap beyond the structured 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?
A single sentence that is front-loaded with the action and resource, followed by the key returned fields. Every word earns its place with no fluff or repetition.
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 description conveys the purpose and expected output sufficiently for a simple list operation with only two parameters and no output schema. However, the absence of pagination behavior disclosure makes it slightly incomplete; an agent might not realize 'all' may require multiple API calls despite the page_token parameter.
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 100%: account_id is documented as 'The GTM account ID' and page_token as 'Continuation token from a previous call to fetch the next page of results'. The description adds no additional parameter meaning, so baseline 3 applies.
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 a specific verb ('List') and resource ('all containers in a GTM account'), and explicitly enumerates the returned fields (IDs, names, public IDs, domains). It naturally distinguishes from sibling tools like gtm_get_container, which targets a single container.
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 use for enumerating containers in an account, but provides no explicit when-to-use guidance or mention of alternatives such as gtm_get_container for a single container. It does not state any exclusions or conditions, leaving the decision to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.