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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds real value beyond them by disclosing the inspection scope — workspace contents plus the live version — and framing the call as a duplicate-prevention precondition. It does not cover auth requirements or how results are shaped, which keeps it from a 5.

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?

Two sentences, zero padding. The returned-content scope is front-loaded and the usage rule follows immediately, so an agent gets purpose and precondition in one pass.

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 necessary work by naming the categories of data returned (tags by type, triggers, live version). What's missing is any indication of shape or granularity — whether tags are enumerated individually or summarized, and how the live version is expressed — but for a one-parameter read tool this is close to sufficient.

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?

There is a single parameter with 100% schema description coverage, and the schema already tells the agent it accepts a GTM-… public id or a container id from gtm_list_containers. The description adds no formatting or sourcing detail beyond that, so the baseline 3 is appropriate for a schema that carries the full burden.

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 the resource — the contents of a Tag Manager container's workspace — and enumerates what is inspected (Analytics tags, Google Ads conversion tags, conversion linker, triggers, live version). The verb is implicit ('what is already in') rather than an explicit 'read/list', but an agent can distinguish it from gtm_install_tracking and gtm_list_containers without opening the schema.

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?

It names the sibling it pairs with and the exact sequencing rule: 'Read this before gtm_install_tracking so nothing is installed twice.' That is an explicit precondition plus the reason for it, leaving nothing to inference about when to call this tool.

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