Rebillia MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It effectively describes the tool's gateway-agnostic nature, the required pre-steps (get_client_token, payment integration), and the prohibition against sending raw card data. However, it doesn't mention potential side effects like whether this creates a default payment method or if there are rate limits.

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 the core purpose. Each sentence adds value: the first states the action, the second explains the gateway-agnostic approach and parameters, and the third provides critical usage instructions. There's minimal redundancy, though it could be slightly more streamlined.

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 creation tool with no annotations and no output schema, the description provides good context about the required workflow and constraints. It covers the essential pre-requisites and integration approach. However, it doesn't describe what the tool returns or potential error conditions, leaving some gaps in completeness.

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 thoroughly. The description adds minimal value beyond the schema by mentioning that billingAddress requires specific fields and that paymentMethodNonce comes from a payment integration, but doesn't provide additional semantic context that isn't already in the schema descriptions.

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 specific action ('Create a payment method for a customer') and distinguishes it from siblings by specifying the resource type (payment method) and being gateway-agnostic. It differentiates from tools like 'update_customer_payment_method' or 'delete_customer_payment_method' by its creation focus.

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 guidance on when to use this tool: after obtaining a gateway client credential via 'get_client_token' and producing a paymentMethodNonce through a payment integration. It also specifies when not to use it ('No raw card data or gateway-specific fields in MCP'), making the usage context very clear.

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