Get a premium (L402-paid) playbook

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

With no annotations, the description carries the full burden and does so well: it discloses the L402 paywall, the typical cost (100 sats), the HTTP 402 challenge and its invoice/macaroon response, and the mandatory two-call handshake with the preimage as proof of payment. This is exactly the behavioral context an agent needs before invoking a payment-gated tool.

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?

Front-loaded with the one-line purpose, then the gating mechanism, then the procedural flow, so each part is findable. It is slightly dense in the middle (payment-server URL and 402 detail) but every sentence carries actionable information.

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 payment-gated, stateless-looking tool with no output schema, the description covers gating, cost, failure mode (402 with challenge payload), and the complete retry path. An agent has everything required to invoke it correctly on both passes.

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 three parameters are already documented, giving a baseline of 3. The description adds real meaning beyond the schema by explaining that macaroon and preimage are omitted on the first call and required on the second, clarifying the two-phase contract rather than just restating field names.

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?

States a specific verb and resource ('Retrieve one premium item from the Ask Refined Element pack by slug') and names the sibling that discovers slugs, so it is immediately distinguishable from search_refined_element_knowledge and the free get_article/get_checklist siblings.

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?

Gives explicit sequencing ('Call this tool FIRST with only the slug', then 'call this tool AGAIN with the same slug plus the macaroon and the payment preimage'), names the discovery alternative, and even points at the recommended Lightning payment helper.

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