hive-mcp-abtest

A/B experiment runner for the A2A network. An inbound-only MCP shim that gives autonomous agents a deterministic, sticky bucket assignment, a conversion-recording endpoint, and a two-proportion Z-test stat-sig calculator. Pricing is per call via x402 on Base USDC.

• $0.001 per abtest_assign
• $0.005 per abtest_record_conversion
• abtest_results is free and read-only

The shim does not run experiments on behalf of the caller. It records assignments and conversions for experiments the caller registers, and returns aggregate counts and a Z-test on demand.

How bucket assignment works

Bucket is SHA-256(experiment_id + "|" + agent_did), with the first four bytes read as an unsigned 32-bit integer, modulo the sum of variant weights. The first call writes the result. Subsequent calls return the same row, so assignment is sticky for the lifetime of the SQLite store.

A variant list is [{ id, weight? }, ...]. Weight defaults to 1 per variant. Pass [{id:"control"},{id:"treatment",weight:3}] for a 25/75 split.

Stat-sig calculator

Two-proportion Z-test with pooled variance over the first two registered variants. Output includes z_score, two-sided p_value, relative_lift, and significant_95 / significant_99 boolean flags.

MCP

• Transport: Streamable HTTP, JSON-RPC 2.0
• Protocol: 2024-11-05
• Endpoint: POST /mcp

Tools:

Tool	Tier	Price
abtest_assign	3	$0.001
abtest_record_conversion	3	$0.005
abtest_results	0	free

REST

Method	Path	Purpose
GET	/v1/abtest	List experiments
POST	/v1/abtest	Create or upsert experiment { id, name?, variants }
GET	/v1/abtest/:id	Get experiment
PUT	/v1/abtest/:id	Update experiment
DELETE	/v1/abtest/:id	Delete experiment
POST	/v1/abtest/assign	{ experiment_id, agent_did, variants? } — $0.001
POST	/v1/abtest/convert	{ experiment_id, agent_did, metric?, value? } — $0.005
GET	/v1/abtest/results	?experiment_id=...&metric=... — Z-test included
GET	/v1/abtest/today	UTC-day assignment + conversion counts
GET	/health	Liveness, version, and DB check

Storage

SQLite at /tmp/abtest.db with three tables: experiments, assignments, conversions. Override with DB_PATH.

Environment

Variable	Default
PORT	3000
ENABLE	true
WALLET_ADDRESS	0x15184bf50b3d3f52b60434f8942b7d52f2eb436e
PRICE_ASSIGN_USDC	0.001
PRICE_CONVERT_USDC	0.005
DB_PATH	/tmp/abtest.db
X402_ENABLED	true

Set X402_ENABLED=false to bypass payment gating in local development.

Quickstart

npm install
npm start
# in another shell
curl -s http://localhost:3000/health
curl -s -X POST http://localhost:3000/v1/abtest \
  -H 'content-type: application/json' \
  -d '{"id":"prompt_v2","name":"prompt v2","variants":[{"id":"control"},{"id":"treatment","weight":3}]}'
curl -s -X POST http://localhost:3000/v1/abtest/assign \
  -H 'content-type: application/json' -H 'x-payment: {}' \
  -d '{"experiment_id":"prompt_v2","agent_did":"did:hive:demo:1"}'

The first call without a paid x402 envelope returns a 402 body with a fresh nonce. Submit a tx hash and payer to /v1/x402/submit to mint a short-lived access token, then retry.

License

MIT. See LICENSE.

Author

Steve Rotzin · steve@thehiveryiq.com · https://www.thehiveryiq.com

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