Agent Query
A family of data-layer clients for agent protocols, plus a policy gate.
The premise: most code that talks to an MCP or A2A server is not itself an agent. It’s a dashboard, an inspector, an approval queue, a notebook. Those apps want what a data layer gives you — a reactive cache, query keys, optimistic updates, lifecycle management — not an autonomous loop.
| Package | What it is |
|---|---|
@johnhenry/mcp-query |
Reactive, cached MCP client. TanStack Query keys + RTK Query tags + LSP-client lifecycle, on the official MCP SDK. |
@johnhenry/mcp-query-tanstack |
TanStack Query bridge — queryOptions/mutationOptions factories with zero extra refetches |
@johnhenry/mcp-gate |
Config-driven MCP security proxy — authorization, DLP redaction, rate limiting, circuit breaking, audit |
@johnhenry/a2a-query |
Reactive A2A client — multi-agent registry, task-handle store, approval broker, on the official A2A SDK |
@johnhenry/a2a-query-tanstack |
TanStack Query bridge for a2a-query |
@johnhenry/acp-query |
Reactive session/turn store and permission broker for the Agent Client Protocol |
The wider family
Section titled “The wider family”All three clients share a protocol-agnostic engine, @johnhenry/agent-query-core — a reactive cache, a human-in-the-loop broker (InteractionBroker), and instrumentation. Wiring one InteractionBroker instance into clients for more than one protocol in the same app unifies approvals, policy, and audit across them.
@johnhenry/mcp-query— Model Context Protocol@johnhenry/a2a-query— Agent2Agent: agent-card registry, task-handle store, approvals@johnhenry/acp-query— Agent Client Protocol: session/turn store and permission broker
Each has a matching TanStack binding (*-tanstack), except acp-query, which doesn’t have one yet.
Renamed 2026-08-23
Section titled “Renamed 2026-08-23”These packages used short handles that didn’t match their repositories. They now match:
| Old | New |
|---|---|
@johnhenry/mcpq |
@johnhenry/mcp-query |
@johnhenry/a2aq |
@johnhenry/a2a-query |
@johnhenry/acpq |
@johnhenry/acp-query |
@johnhenry/mcpq-tanstack |
@johnhenry/mcp-query-tanstack |
@johnhenry/a2aq-tanstack |
@johnhenry/a2a-query-tanstack |
The old names are gone or deprecated — install the new ones. a2aq, acpq, and both old -tanstack names are unpublished; mcpq is deprecated and points here. The short names are reserved for future CLIs.
The rename went deeper than the package name: CLI binaries, cache namespaces, storage keys, and the A2A skillId metadata key all changed. Code written against the old packages needs updating, not just its package.json.
Versions
Section titled “Versions”The renamed packages restarted at 0.0.0 with ^0.0.0 internal ranges. Under npm’s pre-1.0 caret rules that matches only 0.0.0. Pin exact versions. Two exceptions continue their own version lines instead of the shared 0.0.0 restart: @johnhenry/mcp-gate (0.2.1) and @johnhenry/acp-query (0.0.2, after agent-query-core was promoted to a stable 0.1.0).
Both a2a-query and acp-query published early releases before the rename that recommended installing via an @rc dist-tag — that dist-tag and those versions no longer exist. Plain npm install @johnhenry/a2a-query / acp-query gets the current code; ignore any @rc instruction you find in an older cached copy of either README.