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

With no annotations, the description carries full responsibility, and it is explicit that this step does not pay/charge, that the checkout page cannot be skipped, and that refund/payout terms are shown there. It also discloses the needed follow-up polling behavior, which is exactly the kind of side-effect context an agent needs.

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?

Every sentence earns its place: first sentence states the action, then warnings, then the polling contract, then the optional-parameter behavior. It is front-loaded with the core purpose and does not pad.

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?

The description covers the full purchase flow, side effects, and the follow-up contract, which is substantial for a tool with no output schema. It is slightly ambiguous that it says 'return its URL' but later refers to 'the returned sessionId', so the exact response shape is not pinned down.

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%, so the baseline is 3. The description adds real meaning for walletToken by explaining it tops up an existing wallet rather than creating a second one, and it reinforces pack selection via list_packs.

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 opens with a specific action and resource: it creates a Stripe Checkout Session for one smack pack and returns a URL. It also names the follow-up tool (check_purchase) and the downstream walletToken use, which separates it from the sibling 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?

It gives a concrete workflow: hand the URL to the person, poll check_purchase, then use the walletToken with smack_boss. It also explains when to pass an existing walletToken (top up vs. new wallet). It does not state explicit 'don't use this when' exclusions, but the workflow is clear enough.

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