SAP MCP Server

Check Prepaid Session Balance

sap_payments_prepaid_balance

Read-onlyIdempotent

FREE local tool that checks the remaining balance of a prepaid session. No x402 charge. Returns the session ID, remaining USD, total USD, per-call cost, expiry, and call count. Use this before calling sap_payments_call_paid_tool with prepaidSessionId to verify the session still has balance.

SAP MCP execution guidance: Intent: local non-custodial payment/signing bridge. Pricing: free; call directly without x402. Routing: local sap_payments bridge. It may sign x402 payment payloads or user-approved transactions locally, and must never expose keypair bytes. Signer boundary: user-controlled local profile or external signer; OOBE hosted MCP remains non-custodial.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`sessionId`	No	Prepaid session ID returned by sap_payments_start_prepaid.

Output Schema

TableJSON Schema

Name	Required	Description
`totalUsd`	Yes	Original USDC amount deposited when the session was created.
`callCount`	Yes	Number of calls made using this session.
`expiresAt`	Yes	ISO timestamp when the session expires.
`sessionId`	Yes	The prepaid session ID checked.
`remainingUsd`	Yes	Remaining USDC balance in the session.
`perCallCostUsd`	Yes	Cost deducted per granted call.

Schema Changelog

Changes observed during successful MCP inspections.

AddedJul 29, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already indicate read-only, idempotent, non-destructive. The description adds value by stating it is free, local, and does not charge x402. This context supplements the annotations nicely.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The core purpose is stated concisely, but the 'SAP MCP execution guidance' block is verbose and appears to be boilerplate, reducing clarity for the primary use case.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description explains what the tool returns (session ID, balances, costs, expiry, call count) and its role. With an output schema presumably covering return fields, this is complete enough for a simple read tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% and the schema description for sessionId is clear. The description adds no additional meaning beyond the schema, meeting baseline expectations.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states it checks the remaining balance of a prepaid session, with a specific verb and resource. It distinguishes from related tools like sap_payments_fund_prepaid and sap_payments_call_paid_tool by positioning as a prerequisite check.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly tells when to use: 'Use this before calling sap_payments_call_paid_tool with prepaidSessionId to verify the session still has balance.' Also notes it is free and requires no x402 charge.

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

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