Provides tools for interacting with Stripe, enabling checkout discovery, prepaid-credit commerce, and fulfillment status tracking for paid digital delivery.
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type @ followed by the MCP server name and your instructions, e.g., "@CrossingKey MCP server Show my prepaid credit balance."
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Agent-native MCP for governed commerce, x402 payments, paid capabilities, and verifiable receipts.
Endpoint
https://mcp.crossingkeyintelligence.com/mcp
Canonical identity
com.crossingkeyintelligence/crossingkey-mcp
Published source release
3.0.1
Current production release
3.0.1 (public endpoint verified October 12, 2026)
The published v3.0.1 source release and the deployed production runtime are distinct artifacts. On October 12, 2026, the production security update was deployed and verified through MCP initialization, public tool discovery, and HTTP 402 payment challenges. The public source release should not be assumed to contain every production-only security change.
Transport
MCP Streamable HTTP
Related MCP server: swarm-at
CrossingKey MCP is a governed machine-commerce interface for AI agents and authorized software clients.
The public production MCP endpoint returned 26 tools during verification on October 12, 2026. The published v3.0.1 source release previously documented 21 anonymous tools:
7 free discovery and commercial-navigation tools
8 public marketplace tools
6 paid or credit-gated tools
Authenticated sessions additionally expose verification and role-gated marketplace operations.
The operating principle is:
Discovery is free. Evaluation is safe. Payment is explicit. Authority stays bounded. Execution is deterministic. Fulfillment is verifiable.
These seven tools can be used anonymously to understand the provider, available offers, requirements, price, expected result, authorization state, and prepaid-credit options without spending money:
provider.describe
offers.list
requirements.check
cost.estimate
result.preview
execution.preflight
credits.options
The normal discovery sequence is:
provider.describe
→ offers.list
→ requirements.check
→ cost.estimate
→ result.preview
→ execution.preflight
→ credits.options (when prepaid request credits are relevant)A valid commercial flow may reach:
READY_FOR_HUMAN_AUTHORIZATIONand then stop at:
STOPPED_BEFORE_PAYMENTuntil the required buyer authorization and payment conditions are satisfied.
The deployed production public surface includes these marketplace tools:
marketplace.describe
provider.apply
provider.get
capability.get
capability.search
catalog.list
commerce.quote
creator.apply
Discovery, catalog browsing, capability inspection, and quoting do not themselves authorize paid execution.
provider.apply and creator.apply are public intake workflows; applications remain pending and grant no credentials, ownership transfer, or active commercial authority. provider.register is an authenticated administrator operation, not advertised in the anonymous production tool catalog.
These six tools perform valuable computation, validation, or artifact generation and are payment- or credit-gated:
x402.compatibility_audit
mcp.schema_audit
openapi.quality_audit
machine_commerce.readiness_audit
artifact.integrity_manifest
xkey.validate
Current payment models include x402 Base USDC exact-payment flows and prepaid request credits where applicable.
Free discovery does not consume paid execution credits.
Authenticated sessions can expose read-only verification tools including:
approval.verify
idempotency.inspect
receipt.verify
entitlement.inspect
Marketplace sessions may additionally expose role-gated job, receipt, purchase, provider, capability, and settlement operations.
Approval minting remains a local operator action and is not exposed over MCP.
The governed machine-commerce path is:
discover
→ inspect requirements
→ estimate cost
→ preview result
→ preflight
→ authorize
→ pay
→ verify settlement
→ execute
→ issue result
→ bind entitlement
→ issue verifiable receiptPayment alone does not create unrestricted authority.
Authorization, payment verification, execution, fulfillment, entitlement creation, and receipt generation remain separate governed stages.
CrossingKey does not treat an LLM-supplied boolean such as approved: true as buyer authorization.
Where human authorization is required, approval is bound to the relevant commercial context, including the buyer, capability, inputs, quote, idempotency state, and expiration conditions.
Paid execution does not occur merely because an agent asks for it.
The v3.0.1 source exposes public MCP resources for agent comprehension:
crossingkey://discovery-guide
crossingkey://commerce-policy
crossingkey://capability/{name}
These describe the free discovery sequence, commerce policy, and per-capability instructions.
CrossingKey supports governed machine-payment infrastructure including:
x402 v1
x402 v2
Base USDC
prepaid request credits where supported
settlement verification
entitlements
result-bound receipts
idempotent execution
replay protection
The CrossingKey seller wallet boundary is receiver-only.
Agents are not granted unrestricted wallet signing, sending, swapping, bridging, or autonomous seller-spend authority.
The production design includes:
bounded input validation
strict capability schemas
SSRF protections
DNS and address validation
response-size controls
authorization boundaries
approval binding
idempotency protection
payment replay protection
duplicate-settlement protection
deterministic result hashing
entitlement binding
receipt verification
receiver-only seller wallet policy
explicit uncertain-settlement handling
No private keys, wallet secrets, Stripe secrets, API keys, seed phrases, mnemonics, or private customer information belong in this repository.
Recommended entry point:
provider.describe
Canonical MCP endpoint:
https://mcp.crossingkeyintelligence.com/mcp
Canonical identity:
com.crossingkeyintelligence/crossingkey-mcp
Official MCP Registry identity:
com.crossingkeyintelligence/crossingkey-mcp
Website:
https://www.crossingkeyintelligence.com
HAAR research: https://github.com/crossingkey-holdings/crossingkey-public-research/blob/main/research/HAAR.md
Professional evidence: https://github.com/crossingkey-holdings/experience
Developer documentation: https://github.com/crossingkey-holdings/crossingkey-developer-documentation
Open specifications: https://github.com/crossingkey-holdings/crossingkey-open-specifications
HAAR and CrossingKey MCP share concerns such as bounded authority, idempotency, state verification, reconciliation, receipts, and entitlements. HAAR remains a research architecture; this repository and its releases remain authoritative for what CrossingKey MCP actually implements.
Operating online under the handle crossingkey_.
intelligence is the standard.
This server cannot be deployed
Scoped agent execution. Server-side credentials, policy, budgets and verifiable receipts.
Machine-native capabilities with explicit contracts and machine-readable commerce.
Marketplace and payment rail for AI agents: list, buy and settle with signed receipts.
