util_x402_scheme_select

SERVERDelx Mcp A2a SOURCEhttps://api.delx.ai/v1/mcp

Medium RISK CLASS

Category Write

Parameters 22 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/io-github-davidmosiah-delx-mcp-a2a/util-x402-scheme-select.md

WHAT IT DOES

What util_x402_scheme_select does on Delx Mcp A2a

AI agents use util_x402_scheme_select to create or update resources in Delx Mcp A2a, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Delx Mcp A2a environment.

Parameter	Type	Required	Description
`schemes`	array	Yes	Schemes supplied to X402 Scheme Select; used only for this bounded calculation and processed in memory without retention.
`supported_schemes`	array	Yes	Supported Schemes supplied to X402 Scheme Select; used only for this bounded calculation and processed in memory without retention.

Parameters from the server's own tool schema.

RISK

Why util_x402_scheme_select is rated Medium

An AI agent can call util_x402_scheme_select faster than any human can review: one bad instruction and it creates or modifies resources in Delx Mcp A2a by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs util_x402_scheme_select safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Delx Mcp A2a, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For util_x402_scheme_select, this is the rule to start with:

util_x402_scheme_select Rate-limited

util_x402_scheme_select stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "util_x402_scheme_select": {
      "limits": [
        {
          "counter": "util_x402_scheme_select_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Delx Mcp A2a, apply this rule, and every util_x402_scheme_select call is checked against it from then on.

FAQ

Questions about util_x402_scheme_select

What does the util_x402_scheme_select tool do? +

X402 Scheme Select selects the first buyer-supported payment scheme from challenge options from bounded caller-supplied values without an external provider. Call X402 Scheme Select before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for X402 Scheme Select as versioned deterministic JSON. Limitation: Validates metadata only; it never settles payment, signs payloads, contacts a facilitator, refunds funds, or asserts on-chain truth. It is categorised as a Write tool in the Delx Mcp A2a MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does util_x402_scheme_select accept? +

util_x402_scheme_select accepts 2 parameters: schemes, supported_schemes. Required: schemes, supported_schemes. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on util_x402_scheme_select? +

Register the Delx Mcp A2a MCP server in PolicyLayer and add a rule for util_x402_scheme_select: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Delx Mcp A2a. Nothing to install.

What risk level is util_x402_scheme_select? +

util_x402_scheme_select is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit util_x402_scheme_select? +

Yes. Add a rate_limit block to the util_x402_scheme_select rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block util_x402_scheme_select completely? +

Set action: deny in the PolicyLayer policy for util_x402_scheme_select. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides util_x402_scheme_select? +

util_x402_scheme_select is provided by the Delx Mcp A2a MCP server (https://api.delx.ai/v1/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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