create_l402_challenge

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

With no annotations provided, the description carries full burden and does well by disclosing key behaviors: it returns specific outputs (Lightning invoice and macaroon), outlines the payer's required actions (pay invoice and present token), and mentions authentication needs (API key requirement). However, it lacks details on rate limits or error handling.

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 appropriately sized and front-loaded, with three concise sentences that each add value: the first states the purpose, the second explains the return and process, and the third notes prerequisites, with no wasted words.

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 the tool's complexity (payment challenge creation) and lack of output schema, the description is fairly complete, covering purpose, process, and prerequisites. However, it could benefit from more details on output format or error cases to fully compensate for the missing structured data.

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 description coverage is 100%, so the schema already documents all parameters. The description adds no additional meaning beyond what the schema provides, such as examples or usage context for parameters like 'resource' or 'price_sats', meeting the baseline for high coverage.

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 tool's purpose with specific verbs ('create', 'charge') and resource ('L402 payment challenge'), distinguishing it from siblings like 'create_invoice' or 'pay_l402_challenge' by focusing on generating a challenge for accessing resources.

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 clear context on when to use this tool (to charge for resource access) and mentions prerequisites (requires LIGHTNING_ENABLE_API_KEY with Agentic Commerce subscription), but does not explicitly state when not to use it or name alternatives among siblings.

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