Go — Invoke a Capability#

Call a discovered tool with the generic net.CallTool, which is typed on the request and response:

import "context"
 
type WebSearchReq struct {
    Query string `json:"query"`
}
type WebSearchResp struct {
    Results []string `json:"results"`
}
 
rpc, err := net.NewMeshRpc(node)
if err != nil {
    log.Fatal(err)
}
 
resp, err := net.CallTool[WebSearchReq, WebSearchResp](
    context.Background(),
    rpc,
    "web_search",
    WebSearchReq{Query: "how does the capability fold work"},
)
if err != nil {
    log.Fatal(err)
}
fmt.Println(resp.Results)

CallTool[Req, Resp] finds a provider for the named tool, sends a typed request, and decodes the typed response. CallToolStreaming[Req] returns a stream for tools that emit multiple chunks. For raw request/response without the tool abstraction, rpc.Call(...) is the underlying nRPC surface — see Typed RPC with nRPC.

Policy: invocation is authorized, discovery is not#

Seeing a capability does not grant the right to invoke it. A provider enforces scope at call time — an owner-only capability rejects a caller outside its scope, regardless of who can see it. For wrapped MCP tools this is the owner-scope / consent model in Wrap an MCP Server.