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

Beyond the readOnly/idempotent annotations, the description discloses nontrivial behavior: which limits are enforced at save time versus launch time, locked entries being save-but-not-launch for free trials, and the meaning of WILDCARD matching at launch. This is exactly the kind of context that prevents misuse and exceeds what annotations alone provide.

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 description is dense but front-loaded: the core purpose is in the first sentence, and every subsequent sentence adds a distinct piece of operational knowledge. There is no filler or repetition; each sentence earns its place given the subtle engine semantics.

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 carries the burden of explaining what the entries are and how to interpret them, and it does so thoroughly. It covers id provenance, type semantics, save-time vs launch-time limits, and the free-trial caveat, so an agent has enough to invoke the tool and consume its result correctly.

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 tool has zero parameters and the schema coverage is effectively complete, so there are no input parameters to document. The description still adds value by explaining the semantic meaning of output fields (id, type, locked, limits). Baseline 4 for a zero-parameter tool is appropriate.

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 opening sentence states a specific action and resource: list all places a population can run, i.e. the customer's engines/regions. It goes on to distinguish CLOUD, WILDCARD, and PRIVATE entries, making clear this is the engine/load-engine listing tool rather than a generic list. This fully differentiates it from sibling list_* tools.

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 makes the intended use clear: consult this tool to get authoritative loadEngineId values and never invent an engine id. It also provides a concrete decision rule for trial customers (use locked false entries and stay within maxFreeTrialBotsPerTest). It does not explicitly name alternative tools or say when not to use it, so it falls just short of a 5.

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