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

The description discloses that Mithrandir never signs or holds private keys and that settlement atomically activates the account and returns an API key once within a bounded retry window. These details go beyond the annotations and help an agent understand side effects, though failure/error behavior is not covered.

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?

Three short sentences are front-loaded with the main purpose and contain no padding. Security and settlement behavior are placed efficiently after the primary operation.

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 main outcome and security posture, but with no output schema it omits the challenge response format, failure modes, and the exact condition that selects 'get challenge' versus 'submit signature.' It is adequate but leaves notable gaps for a payment mutation tool.

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 0%, so the description needed to explain the parameters. It only indirectly identifies payment_signature as a wallet-produced signature and gives no meaning to onboarding_id or onboarding_secret, leaving the agent without enough information to construct a correct call.

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 names a specific resource (x402 payment challenge for an onboarding session) and the two operations: getting a challenge or submitting a payment signature. It is clear about the tool's function, though it does not explicitly contrast it with sibling onboarding tools such as status or reconcile.

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 states the two use modes directly: obtain a payment challenge or submit a wallet-produced signature. This gives clear context for when to call the tool, but it does not spell out when to prefer a sibling or what prerequisites must hold.

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