[BUG] MCP connector tools bound on Claude desktop but not surfaced on mobile chat surface

[jerylcook-nearsight]

What happened?

I'm reporting a reproducible bug in the Claude mobile app where MCP tool calls are never invoked. The client successfully completes the handshake but then restarts the session instead of calling tools.

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Environment

• Client: Claude mobile app (iOS/Android)
• Transport: Streamable HTTP (MCP spec 2025-11-25)
• Server: Spring AI 2.0.0-RC2, Java, deployed at https://demo.nearsight.ai/mcp
• Auth: OAuth 2.1 (Bearer token)
• Claude web (desktop): works correctly — tools are invoked successfully

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Behavior Observed

The mobile client repeatedly completes the MCP discovery handshake but never proceeds to tool invocation. Instead it restarts the session every ~25 seconds:

1. POST /mcp (session=null) → initialize → 200, new session assigned
2. POST /mcp → notifications/initialized → 202
3. POST /mcp → resources/list → 200
4. POST /mcp → tools/list → 200
5. POST /mcp → prompts/list → 200
6. ← no tool call ever arrives →
7. POST /mcp (session=null) → initialize → 200, NEW session (loop repeats)

This loop was observed repeating at least 3 times within a 2-minute window. The user sees "cannot reach server" in the mobile UI.

Additional anomaly: resources/list is sent twice within the same session with the same request id:1, suggesting a client-side retry/state issue during discovery.

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What the server logs confirm

• Auth token is present (Authorization: Bearer) on every single request — this is not an auth issue
• All server responses are 200/202 — the server is handling everything correctly
• No tool call (tools/call) POST ever arrives at the server
• The same behavior reproduces across multiple fresh sessions

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Expected Behavior

After completing discovery (tools/list, resources/list, prompts/list), the mobile client should send a tools/call POST when the user invokes a tool, consistent with how the desktop web client behaves.

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Impact

MCP tool calls are completely non-functional on Claude mobile for Streamable HTTP connectors. The desktop web client works correctly against the identical server, confirming this is a mobile client regression.

here's the full configuration detail. Please note again that our MCP Server works successfully in Claude UI (Desktop), the ChatGPT UI (Desktop), and the ChatGPT mobile app. the issue is only in Claude Mobile.

Server stack

Spring AI 2.0.0-RC2 (Java), WebMvcStreamableServerTransportProvider
Transport: Streamable HTTP at https://demo.nearsight.ai/mcp
Protocol version negotiated: 2025-11-25
Auth: OAuth 2.1 / Clerk, Bearer JWT (at+jwt), validated via Spring Security resource server
Fronted by Cloudflare → nginx ingress → Spring Boot on LKE
Capabilities advertised: tools, resources, prompts
Mobile client identifies as: Anthropic/ClaudeAI version 1.0.0

What the server observes (every mobile session, reproducible):

initialize (session=null) → 200, new session assigned
notifications/initialized → 202
resources/list → 200
tools/list → 200 (correct tool count parsed; UI shows it)
prompts/list → 200
No tools/call ever arrives
Session restarts ~25–80s later, loop repeats
Auth header is present on every request — not an auth failure. All responses 200/202.

Notable client-side anomaly: tools/list and resources/list are each sent twice within the same session using the same JSON-RPC id (id:1). This duplicate-ID retry appears in every captured mobile session and never on web desktop.

Exact mobile model response to a tool-invocable query ("what are my asset types"):

"I can't pull this from your live NearSight server in this chat — I don't have the MCP tools callable here (they're only available when building an artifact against demo.nearsight.ai/mcp, not in the regular chat tool surface)."

The model then fabricated an asset-type answer from conversation context rather than calling the tool. The same query on web desktop invokes the tool and returns the correct result.

Environment: Native Claude mobile app (not browser). Identical connector, identical server, identical account — only the surface differs.
Please let me know if you need the full server debug logs — I have timestamped traces covering multiple session restart cycles.

What did you expect to happen?

Expected Behavior

After completing discovery (tools/list, resources/list, prompts/list), the mobile client should send a tools/call POST when the user invokes a tool, consistent with how the desktop web client behaves.

Steps to reproduce

nearsight-mobile-mcp-logs.txt

Area

MCP Connector (adding/managing servers)

MCP Server (if applicable)

https://demo.nearsight.ai/mcp

Error messages or logs

Exact mobile model response to a tool-invocable query ("what are my asset types"):

"I can't pull this from your live NearSight server in this chat — I don't have the MCP tools callable here (they're only available when building an artifact against demo.nearsight.ai/mcp, not in the regular chat tool surface)."

Additional context

No response

[6vphw8kbyv-sys]

Confirming the same behavior here.
Running a custom MCP server (streamable-http transport) on a lightweight cloud instance behind a Cloudflare tunnel. Everything was working fine until around June 22–23.
Symptoms:

On both the web client and mobile app, the MCP handshake completes successfully (tools are listed and visible).
However, any actual tools/call invocation never reaches the server — the response hangs for 25–80 seconds, then fails with "response incomplete."
Once this happens, the conversation window becomes completely unresponsive — resending, refreshing, and starting a new conversation all fail if the MCP is still enabled.
The only workaround is to disable MCP invocation entirely (e.g., removing references from the profile prompt that would trigger automatic tool calls).

Key diagnostic: The exact same MCP server connects and responds to tool calls perfectly fine via Claude Code (CC). The server logs confirm CC's requests arrive normally, while chat-client tools/call requests simply never show up. This rules out any server-side issue.
Environment: Tencent Cloud lightweight instance, Cloudflare tunnel, streamable-http transport.
Would love to see this prioritized — it effectively makes MCP unusable on the chat platform. Happy to provide server logs or additional details if helpful.

[darthrootbeer]

Adding a specific use case that seems related to this: I want to have a hands-free voice conversation with Claude on the iPhone app (voice mode), where Claude also has access to an MCP server (in my case, an Obsidian vault MCP server) so it can pull live context mid-conversation.

Based on this thread, it sounds like the answer is "no, mobile doesn't invoke MCP tools at all right now, voice or otherwise" — since the client hangs after tools/list and never gets to tools/call regardless of input method. Can anyone confirm that's the case? i.e. is voice mode a separate blocker on top of this, or would fixing this mobile tool-invocation bug also unblock MCP tool use during voice conversations?

Would love to see this fixed — hands-free voice + live tool/context access feels like an obvious pairing (e.g. mobile Siri-style workflows), and right now it's broken end to end on mobile.

[jerylcook-nearsight]

This is now working as of today, 7/25, after trying again from mobile. It would be nice to know or confirm what the fix was, but grateful regardless :).. others who commented link on this ticket. Hopefully it works for you as well.

[jerylcook-nearsight]

Claude mobile now works fully I assume it was fixed on the latest claude mobile release.

[xcc-mastercard]

Additional reproduction — custom connector, mobile chat surface only

Confirming this reproduces with a custom OAuth MCP connector on my end too.

Setup: Custom remote MCP connector with OAuth, standard SSE/POST transport.

Repro:

1. Added the custom connector (also tested with a fresh connector name — same result).
2. Completed OAuth on iOS. Server-side logs confirm the discovery handshake and tools/list return HTTP 200.
3. iOS app never shows the tool badge and stays on "Connect." Chat reports the connector isn't available as a tool.

Controls that isolate it to custom connectors + mobile chat:

• A different, smaller connector on the same device/account works fine — badge appears, tools invocable in chat.
• The same custom connector works correctly on Claude desktop/web with its full tool catalog.
• Only mobile chat fails; the connector shows up for artifacts but isn't invocable in conversation.

Additional test: Reduced the tool catalog down to a handful of tools to rule out payload size as the cause. Same failure — still no badge on mobile. This points to something in how the mobile client wires discovery to invocation for custom (non-directory) connectors specifically, rather than a size/parsing issue.

Also reported via official support. Happy to share more detailed traces privately if that's useful for debugging.