MCP 服务器

hive-mcp-agent-quota

Per-agent quota meter for the A2A network, enabling quota checks with USDC settlement on Base L2 via x402 envelopes.

README

hive-mcp-agent-quota

Per-agent quota meter for the A2A network. Each call to quota_check consumes one or more units against an agent's DID and is settled at $0.001 USDC per unit on Base L2 via the x402 envelope. Inbound only. ENABLE=true by default.

Brand color: #C08D23 (Pantone 1245 C, Hive Civilization gold).

Surface

Layer	Endpoint	Description
MCP	`POST /mcp`	JSON-RPC 2.0, Streamable-HTTP, protocol `2024-11-05`.
Discovery	`GET /.well-known/mcp.json`	Tool list and transport metadata.
REST	`POST /v1/quota/check`	Consume units for a DID. 402 if no balance and no proof.
REST	`GET /v1/quota/balance?did=…`	Read remaining quota for a DID.
REST	`GET /v1/quota/today`	UTC-day ledger snapshot.
REST	`GET /v1/quota/estimate?units=N`	Asking and floor in USDC for N units.
Health	`GET /health`	Liveness, pricing, recipient address.
Root	`GET /`	HTML for browsers, JSON for agents (Accept-header sniff). JSON-LD `SoftwareApplication`.

Tools

Name	Tier	Cost	Description
`quota_check`	1	$0.001/unit	Consume N units for a DID via x402.
`quota_balance`	0	free	Remaining quota for a DID.
`quota_topup_estimate`	0	free	Asking and floor for N units.

Pricing and the barter floor

Pricing inherits the hivemorph barter pattern. Every 402 envelope advertises both amount_usd (asking) and accept_min_usd (floor). A client may submit a proof whose on-chain paid amount is anywhere in [floor, asking] and the shim accepts it.

Defaults, all overridable by environment variable:

Variable	Default	Notes
`QUOTA_CHECK_PRICE_USDC`	`0.001`	Per-unit asking price.
`HIVE_X402_FLOOR_PCT_DEFAULT`	`0.70`	Floor as fraction of asking.
`HIVE_X402_FLOOR_MIN_PCT`	`0.30`	Hard lower clamp.
`HIVE_X402_FLOOR_MAX_PCT`	`0.95`	Hard upper clamp.

So a 1-unit check at the defaults advertises asking $0.0010 and accept-min $0.0007. A 100-unit check advertises asking $0.1000 and accept-min $0.0700. The floor never falls below MIN_PCT of asking and never exceeds MAX_PCT.

Settlement

Field	Value
Chain	Base L2
Asset	USDC
Contract	`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`
Recipient	`WALLET_ADDRESS` env, default `0x15184bf50b3d3f52b60434f8942b7d52f2eb436e`
Verification	`provider.getTransactionReceipt(tx_hash)` against `BASE_RPC_URL`, decode USDC `Transfer` logs to recipient, sum amount in 6-decimal units, compare to `accept_min_usd`.
Signature (optional)	`ethers.verifyMessage(message, signature)` recovers payer; rejected if it disagrees with the on-chain `from`.

No mocks. The on-chain check is a real RPC read against Base mainnet.

Storage

SQLite at QUOTA_DB_PATH (default /tmp/quota.db), three tables:

quotas (did, units_purchased, units_consumed, first_seen, last_seen)
checks (id, did, unit_count, granted, remaining, tx_hash, paid_usdc, ts)
topups (id, did, units, paid_usdc, tx_hash UNIQUE, payer, ts)

tx_hash is UNIQUE on topups to make replay a 409.

x402 envelope

A quota_check call with no prepaid balance and no proof returns:

{
  "error": "payment_required",
  "x402_version": 1,
  "payment": {
    "nonce": "…",
    "amount_usd": 0.001,
    "accept_min_usd": 0.0007,
    "accepts": [{
      "chain": "base",
      "asset": "USDC",
      "contract": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "decimals": 6,
      "recipient": "0x15184bf50b3d3f52b60434f8942b7d52f2eb436e",
      "scheme": "exact"
    }],
    "expires_at": 1761600000,
    "tier": 1,
    "product": "agent_quota_check",
    "unit_count": 1,
    "price_per_unit_usd": 0.001,
    "floor_pct": 0.70
  }
}

The client sends USDC to the recipient on Base, then resubmits the same request with an X-Payment header containing the proof:

X-Payment: {"nonce":"…","chain":"base","tx_hash":"0x…","payer":"0x…","signature":"0x…","message":"hive-quota:<nonce>"}

signature and message are optional. If supplied, the recovered address must match payer and the on-chain from.

Environment

Variable	Default	Notes
`PORT`	`3000`
`ENABLE`	`true`	Set to `false` to disable `tools/call`.
`WALLET_ADDRESS`	`0x15184bf50b3d3f52b60434f8942b7d52f2eb436e`	USDC recipient on Base.
`QUOTA_CHECK_PRICE_USDC`	`0.001`	Per-unit asking.
`HIVE_X402_FLOOR_PCT_DEFAULT`	`0.70`
`HIVE_X402_FLOOR_MIN_PCT`	`0.30`
`HIVE_X402_FLOOR_MAX_PCT`	`0.95`
`BASE_RPC_URL`	`https://mainnet.base.org`
`DEFAULT_QUOTA_UNITS`	`0`	Free units credited on first sight of a DID.
`QUOTA_DB_PATH`	`/tmp/quota.db`

Running locally

npm install
node server.js

Then:

curl -s http://localhost:3000/health
curl -s -X POST http://localhost:3000/mcp \
  -H 'content-type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'
curl -s 'http://localhost:3000/v1/quota/today'

Hard rules

Inbound only. The shim never originates an outbound payment.
No private key in the repo. Verification is read-only.
No custody. The recipient address belongs to the operator, not the shim.
Returns are advisory until the on-chain receipt is confirmed by BASE_RPC_URL.

Council provenance

Tier A position 3. 2026-04-27. Inbound metering surface, symmetric to hive-mcp-barter (outbound counter-offer) and hive-mcp-auction (inbound reverse-Dutch).

License

MIT. See LICENSE.

Hive Gamification

This MCP server is part of the Hive Civilization gamification surface (10-mechanic capability taxonomy).

Capability taxonomy: https://hive-gamification.onrender.com/.well-known/hive-gamification.json
Centrifuge dashboard: https://hive-gamification.onrender.com/.well-known/hive-centrifuge.json
Consolidated OpenAPI: https://hive-gamification.onrender.com/.well-known/openapi.json

Surface tags: gamification.spec.v1 · gamification.surface.public · gamification.signal.read-only · gamification.settlement.real-rails

Real rails on Base L2 (USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913). Read-only signal layer. Brand gold #C08D23.