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

With no annotations provided, the description carries the burden of disclosing behavior. It clearly states that Robyn does not sign, holds no payee keys, and returns a digest for the payee to sign, which is a critical counterintuitive behavior. It also explains the rationale. However, it does not mention whether the request is stored, expiration handling, or error scenarios, so it's not fully exhaustive.

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 two sentences, front-loaded with the action ('Build a canonical payment request') and immediately states the key output and signing requirement. It includes a useful rationale without any fluff. Every sentence earns its place.

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 no output schema and no annotations, the description does well to explain the process, the signer, and the return value (digest). It also situates the tool within the payment request workflow. However, it could be more complete by mentioning what happens after signing or how the digest is used, though that is likely covered by sibling tools.

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 50%, meaning memo, token, and expiresInSec lack schema descriptions. The tool description lists all parameters (payee, chain, token, amount, memo, expiry) but adds little beyond their names. It doesn't clarify formats, defaults, or relationships (e.g., what 'expiry' maps to, token representation). This is adequate but not compensatory for the undocumented fields.

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 builds a canonical payment request and returns a digest for the payee to sign. It distinguishes itself from siblings like robyn_payment_request_settlement and robyn_payment_request_verify by focusing on the prepare step, and explicitly clarifies that Robyn does not sign these requests.

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 when-to-use guidance: 'Use this when an agent needs to ASK another agent for money in a way the payer can actually check.' It also implicitly explains when not to use it (when Robyn should sign) by stating Robyn doesn't sign and holds no payee keys, effectively differentiating from signing/verification tools.

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