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

Annotations already cover read-only safety, so the description's value is in disclosing the payload: version number/name/approximate save time, object counts, paused-tag count, and unpublished workspaces. That is concrete, non-obvious return context. It stops short of saying whether unpublished-change detection is per-user or account-wide, or how 'roughly when' is derived.

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 front-loaded sentence listing the reported items, with zero filler. The colon-and-list construction makes the payload scannable, though a single sentence of that length is slightly dense.

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 output schema, the description does the work of describing the return shape and does it thoroughly for a read-only summary tool. Remaining gaps are about aggregation semantics and error cases, which are minor for this tool type.

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 description never mentions the single optional `container` parameter; the schema carries it at 100% coverage, including the 'GTM-ABC123' format and the single-container default. With full schema coverage the baseline of 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?

Opens with a specific scope statement ("What's live in a GTM container") and enumerates exactly what is reported: published version identity, tag/trigger/variable counts, paused tags, and workspaces with unpublished changes. It implicitly separates itself from gtm_list_tags / gtm_list_triggers_and_variables by returning counts rather than lists, but never names those siblings.

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 or when-not-to-use guidance is given. The agent must infer that this is the summary entry point rather than gtm_audit_container or gtm_version_history, and nothing states prerequisites such as needing a container chosen from gtm_list_containers first.

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