# MCP call tool

> Tag 15: the server relays an MCP exchange the container asked of the client’s servers, its params verbatim; the client answers with exactly one channel response, a result or an error, which the server relays to the container.

Canonical: https://provider.diverge.network/2.3.0/endpoints/containers-agents-run/server/mcp-call-tool/
Specification revision: 2.3.0

The server opens this channel when the container's proxy sends the
corresponding MCP ask on `/requests`. The params are relayed
verbatim; the client's one answer is relayed back.

- **The request.** The tag byte `15` followed by the params as JSON.
  [Request](/2.3.0/endpoints/containers-agents-run/server/mcp-call-tool/request/) states its form.
- **The response.** Exactly one channel response, a result or an
  MCP error, and the channel response finish.
  [Response](/2.3.0/endpoints/containers-agents-run/server/mcp-call-tool/response/) states the sequence.
- **The conduit.** The server relays the one channel response to the
  proxy's [`/mcp/call-tool/{channel}`](/2.3.0/proxy/mcp/call-tool/) as one
  message and closes that connection. The server does not read the
  params or the answer, and does not send the ask twice.