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

The description goes beyond annotations by disclosing revenue split (70/30), classifying the transaction as a content sale rather than a donation, and confirming that it grants access to every sermon. While the idempotentHint is already in annotations, the description reinforces it and adds valuable financial and access context.

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 concise yet information-dense, covering all key aspects (action, payment, discovery, revenue split, idempotency) without redundancy. Each sentence earns its place, and the structure is clear and front-loaded.

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 purchase tool, the description is remarkably complete: it explains what a bundle is, how to acquire it (credits or x402), how to find it, the financial terms, and idempotency. There is no output schema, so return format is not required. The description leaves no obvious gaps.

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 schema fully describes bundle_id, including its origin as product_id from browse_catalog. The description adds marginal value by referencing the use of bundle_id in pay_with_x402, but this is more about an alternative flow than the parameter's semantics for this tool. With 100% schema coverage, a baseline score of 3 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 description clearly states the verb 'buy' and the resource 'bundle (a sermon series)', and explains it grants access to every sermon. It distinguishes itself from sibling purchase_sermon by focusing on bundles and mentions how to find bundles via browse_catalog. The explicit reference to 'same terms as purchase_sermon' further differentiates it.

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 provides explicit guidance: use this tool to purchase bundles with prepaid credits; if no credits, use pay_with_x402 with the same bundle_id. It also directs users to browse_catalog for discovery. This gives clear usage context and alternatives.

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