@appcontextprotocol/cli

acp is temporary developer inspection tooling for the private JSON-RPC/WebSocket compatibility channel. It is useful while instrumenting an application, but it is not the public agent boundary and does not prove that the direct or brokered MCP path works.

Install the public alpha globally, or replace acp in any command below with npx --yes @appcontextprotocol/[email protected]:

npm install --global @appcontextprotocol/[email protected]

Then run:

acp ls
acp describe com.acme.crm
acp state com.acme.crm
acp state com.acme.crm customers
acp call com.acme.crm change_customer_plan --args '{"customerId":"cus_1","newPlan":"pro"}'
acp watch com.acme.crm

Add --json to ls, describe, and call for machine-readable output. Compatibility failures print ACP error <code>: <message> to standard error and exit with status 1.

These commands currently select by appId and are intended only for controlled, single-instance development. They do not provide the exact-instance routing required by the MCP broker. For public-path testing, connect an ordinary MCP client directly to one manifest's Streamable HTTP endpoint or configure the local stdio broker and use:

1. apps_list to obtain appId and opaque instanceId;
2. app_describe, app_state, or app_call with both identifiers; or
3. the broker's revision-bound typed tools and per-instance resources.

The direct application endpoint and broker currently support MCP tool-list and resource-list change notifications plus resource-update notifications. watch describes only the private compatibility subscription path: it has no replay or automatic reconnect, and events emitted while disconnected are not delivered.

The CLI is one of the three public packages, but its compatibility implementation is transitional. MCP-native inspection should replace that implementation without exposing @appcontextprotocol/client as a public dependency; the published tarball bundles the private client code and passes clean-consumer verification.