l402_challenge_create

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

Without annotations, the description carries the full burden. It discloses the output (WWW-Authenticate header for HTTP 402) and the creation of invoice and macaroon, but does not mention side effects, persistence, auth requirements, or potential state changes. This is partial transparency.

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?

Two sentences, front-loaded with the primary action and output. Every word adds value with no redundancy.

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 5-parameter tool with no output schema and no annotations, the description is too sparse. It omits parameter explanations, output format details, prerequisites, and how the challenge integrates with verification tools, leaving significant gaps for an agent to invoke it correctly.

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?

Input schema has 20% description coverage (only amount_sats is described). The description does not compensate by explaining the other four parameters. It references 'resource' in the purpose but not its parameter semantics, leaving most parameters undefined.

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 action: 'Create an L402 payment challenge (invoice + signed macaroon)' with a specific purpose 'to protect a resource behind a Lightning paywall.' It also names the return value, distinguishing it from sibling payment tools like l402_pay and l402_payment_verify.

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 implies use when protecting a resource behind a Lightning paywall, which provides clear context. However, it does not explicitly name alternatives or exclusion criteria, so it falls short of the highest bar.

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