Class McpClientExperimental

The result of the last (or in-flight) initialize call — protocolVersion/serverInfo/capabilities.

The Mcp-Session-Id this client was bound to on initialize, or undefined before the first call.

tools/call. Throws McpToolError when the tool reported failure (result.isError: true) — never returns a result the caller has to remember to check .isError on.

Runs the initialize handshake, capturing the Mcp-Session-Id response header for every later call. Safe to call more than once — concurrent callers share one in-flight request; a session already established is NOT re-initialized.

Walks tools/list to completion, following nextCursor until the server stops issuing one, and returns every descriptor in server order.

The loop is bounded twice, because "follow the cursor until it stops" is an unbounded instruction handed to a remote party:

• Page cap (McpListAllToolsOptions.maxPages, default MCP_DEFAULT_MAX_TOOL_LIST_PAGES) — a server that keeps issuing fresh cursors forever cannot spin this client forever.
• Repeat-cursor guard — a server that hands back a cursor it already handed back is looping; that is caught on the first repeat instead of burning the whole page budget on the same page.

Both bounds throw McpProtocolError rather than silently returning a truncated catalog, because a partial tool catalog is indistinguishable from a narrower server authorization and must never be mistaken for one.

Neither bound helps against a server that accepts a page request and never answers it, so McpListAllToolsOptions.signal is threaded into the handshake and every page — that is the only bound on a request in flight.

tools/list — paginated per MCP 2025-03-26; pass cursor back from a prior nextCursor to fetch the next page.

Drops the negotiated Mcp-Session-Id and initialize result so the next call re-handshakes. Callers use this to reconnect — a new server session may advertise a different tool catalog, so whoever calls this is responsible for invalidating anything derived from the old one (StudioAgentSession.reconnect invalidates its tool catalog here).

Subscribes to the server's standalone GET /mcp SSE stream and reports every server-initiated notification — notifications/tools/list_changed above all — until the subscription is closed, the server declines the channel, or the reconnect budget runs out.

The returned stream reads this client's session id on every connect attempt, so a resetSession plus re-handshake is carried automatically. Call this only after (or alongside) a request that has established a session: an un-handshaken client sends no Mcp-Session-Id, which a session-enforcing server rejects.

Nothing else on this client starts a stream — a consumer that never calls this never opens one.