GTM: Find container by ID

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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds real substance by disclosing what the call yields (accountId and containerId) despite the absence of an output schema, and by listing the accepted ID families. It stops short of describing not-found behavior or whether linked destination IDs resolve across accounts.

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 with no filler, and the accepted ID formats are packed in efficiently. The phrasing 'Finds the container with accountId and containerId for a public ID' is slightly tangled grammatically but still parses in a single read.

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?

For a single-parameter lookup annotated as read-only and open-world, the definition covers input formats and the shape of the result, which is what an agent needs to call it and use the answer. Only failure/not-found semantics are absent, a minor gap at this complexity level.

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 coverage is 100% and the single 'id' parameter already carries an example, so the schema does most of the work. The description modestly extends this by naming G-XXXX linked destination IDs, a format the schema example does not show, which justifies staying at the top of the baseline band.

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 and resource (finds the container) and clarifies the mapping performed: a public ID such as GTM-XXXX, G-XXXX, or AW-123456789 resolves to accountId/containerId. That distinguishes it from listing tools like gtm_list_accounts, though it does not name a specific sibling alternative.

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 use case is implied — resolve a public/measurement/pixel ID into GTM account and container identifiers, presumably before calling other gtm_* tools — but there is no explicit when-to-use or when-not guidance and no alternative named. The agent must infer the workflow position from the description alone.

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