Worker-side MCP activities and a pooled-connection subsystem.
The Gemini SDK's automatic-function-calling loop runs inside the workflow, where it would otherwise call McpClientSession.list_tools / call_tool directly (network I/O — forbidden in a workflow). The workflow-side TemporalMcpClientSession shim redirects those two methods to the {server}-list-tools / {server}-call-tool activities defined here, so the real mcp.ClientSession lives only on the worker.
A single live session per server is held open in the worker process and reused across activity invocations, with idle eviction — modeled on the strands plugin's _temporal_mcp_client. The MCP transport and ClientSession are anyio context managers whose cancel scope is bound to the task that enters them, so a dedicated owner task (_ConnectionRecord._run) holds them open for the connection's lifetime while concurrent activities on the same event loop call through the shared session.
| Function | build |
Return the per-server {server}-call-tool activity for registration. |
| Function | build |
Return the per-server {server}-list-tools activity for registration. |
| Function | build |
Build the list-tools and call-tool activities for every registered server. |
| Async Function | get |
Return the cached session for server, opening one lazily if needed. |
| Type Alias | |
Undocumented |
| Class | _ |
A single MCP session held open by a dedicated owner task. |
| Async Function | _evict |
Undocumented |
| Constant | _CONNECTIONS |
Undocumented |
| Constant | _MCP |
Undocumented |
str, factory: McpSessionFactory, idle_timeout: timedelta | None = None) -> Callable:
(source)
¶
Return the per-server {server}-call-tool activity for registration.
Reuses the same lazily-opened, idle-evicted worker-process MCP session as {server}-list-tools. Returns the raw mcp.types.CallToolResult — including tool-level error results (isError=True), which the model is meant to see; only transport/protocol failures raise (and evict).
str, factory: McpSessionFactory, idle_timeout: timedelta | None = None) -> Callable:
(source)
¶
Return the per-server {server}-list-tools activity for registration.
Reuses a lazily-opened, idle-evicted worker-process MCP session. Returns the raw mcp.types.ListToolsResult so the workflow-side shim can hand it to the Gemini SDK exactly as a live session would (preserving the full tool parameter schema).
dict[, idle_timeout: timedelta | None = None) -> list[:
(source)
¶
Build the list-tools and call-tool activities for every registered server.
str, factory: McpSessionFactory, idle_timeout: timedelta) -> tuple[:
(source)
¶
Return the cached session for server, opening one lazily if needed.
Concurrent first-callers dedupe onto a single connect handshake by awaiting the same record. The returned record is acquired; the caller must release() it once the call completes so idle eviction can resume.