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

With no annotations, the description carries the full burden of behavioral disclosure, and it does so thoroughly. It states validity duration (24h), that payments are simulated, that the credential settles nothing, that it works only on the demo store, and that no human login is involved. These are meaningful behavioral traits beyond the mere fact of creating a key.

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 three sentences and every sentence earns its place: purpose and validity, two usage methods with a clear conditional, and important limitations. The most essential information is front-loaded, and there is no redundancy or filler.

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?

Given that the tool takes no parameters and an output schema exists to describe the return value, the description covers everything an agent needs: what the credential is, how long it lasts, exactly how to present it, and what its limitations are. The sibling context confirms checkout tools exist, so the reference to `agent_key` is actionable.

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 has 100% coverage of that fact, so the baseline is 4. The description adds relevant contextual guidance about how the returned credential should be used, even though it does not define any input parameters because none exist.

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 identifies the action ('Get') and the resource ('temporary sandbox credential'), and gives concrete purpose: authenticating to the demo store. It distinguishes itself from all sibling tools by being the only credential/authentication tool in the list, rather than a cart, checkout, product, or search operation.

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 provides explicit, actionable usage instructions: present the credential as an `Authorization: Bearer` header, or pass it as the `agent_key` argument to checkout tools when headers cannot be set. It also sets expectations about scope ('works only on the demo store') and simulation ('settles nothing'), making the correct invocation context clear.

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