MCP sampling
Category: protocol
Lets the MCP server request an LLM completion from the client during a tool call (server-initiated sampling).
Support by client
| Client | Status | Notes | Verified |
|---|---|---|---|
 Claude Web | unsupported | Client did not declare sampling capability. Response: 'Result: the sampling probe failed. This client didn't declare the sampling capability at initialization, so the server's sampling/createMessage request couldn't complete. Sampling is unsupported here (call id: 42ed37).' Call id: 42ed37. | 2026-07-05T16:01:12.439Z |
| Claude Desktop | unsupported | Plain text response only; the tool result states the client never declared the sampling capability, so sampling/createMessage was not supported on this host. | 2026-07-08T15:01:59.154Z |
| Claude Mobile | unsupported | Probe self-reports: client did not declare sampling capability during initialize - sampling/createMessage unsupported (call id 185c01). Automated via Mirroir. | 2026-07-09T17:55:25.862Z |
| Claude Voice | unknown | — | |
| Claude Code | unsupported | The model's reply echoed the probe's server-minted verdict: the client did not declare the sampling capability during MCP initialize. | 2026-07-04T15:49:51.406Z |
 ChatGPT Web | unsupported | Probe tool text 'No sampling capability in the client's initialize request.' rendered inline in message body — ChatGPT web did not declare sampling capability during MCP initialize handshake. | 2026-07-05T15:00:01.375Z |
| ChatGPT Mobile | unknown | — | |
| ChatGPT Voice | unknown | — | |
| ChatGPT Desktop | unknown | — | |
| Codex CLI | unsupported | The model's reply echoed the probe's server-minted verdict: the client did not declare the sampling capability during MCP initialize. | 2026-07-04T15:52:29.276Z |
 Siri | unknown | — | |
| Apple AI (ChatGPT) | unknown | — | |
 Gemini Web | unknown | — | |
| Gemini Mobile | unknown | — | |
| Gemini Voice | unknown | — | |
| Gemini CLI | unsupported | Client did not declare the sampling capability during MCP initialize. | 2026-07-08T15:43:49.758Z |
 Antigravity | unknown | — | |
 Cursor | unknown | — | |
| Cursor CLI | unsupported | Client did not declare the sampling capability during MCP initialize. | 2026-07-04T15:43:00.496Z |
 VS Code (Copilot Chat) | unknown | — | |
 GitHub Copilot CLI | unsupported | Client did not declare the sampling capability during MCP initialize. | 2026-07-04T15:43:05.285Z |
 Windsurf | unknown | — | |
 Zed | unknown | — | |
 Perplexity Web | unknown | — | |
| Perplexity Mobile | unknown | — | |
| Perplexity Voice | unknown | — | |
| Comet Browser | unknown | — | |
 Grok Web | unknown | — | |
| Grok Mobile | unknown | — | |
| Grok Voice | unknown | — | |
| Grok CLI | unsupported | Client did not declare the sampling capability during MCP initialize. (tool_use event and debug log both missed; inferred toolCalled from call-id echo) | 2026-07-04T15:49:58.608Z |
 Warp | unknown | — | |
 Amp | unknown | — | |
 Goose CLI | unsupported | The model's reply echoed the probe's server-minted verdict: the client did not declare the sampling capability during MCP initialize. | 2026-07-04T15:46:11.062Z |
| Antigravity CLI | unsupported | Client did not declare the sampling capability during MCP initialize. (tool name not in reply; inferred toolCalled from call-id echo) | 2026-07-04T15:43:01.093Z |
 JetBrains AI Assistant | unknown | — | |
 Ollama | unknown | — | |
 LM Studio | unknown | — |