MCP servers for ChatGPT (Codex) · Research
Best research MCP server for ChatGPT (Codex), tested
In ToolPassed's hands-on tests in ChatGPT (Codex), arXiv MCP is our provisional candidate for research: it passed install, connect, tools and an agent task on 2026-10-15. We ran 4 research MCP servers in ChatGPT (Codex); 3 passed every step; not a pass: Paper Search MCP (failed).
Last tested · runs from 2026-10-15 to 2026-10-22 · one run per server · How we test
Results in ChatGPT (Codex)
| Server | ChatGPT (Codex) |
|---|---|
| arXiv MCP Research | Passed 2026-10-15 · install, connect, tools, agent task |
| Hugging Face MCP Server Research | Passed 2026-10-22 · install, connect, tools, agent task |
| Simple arXiv MCP Research | Passed 2026-10-19 · install, connect, tools, agent task |
| Paper Search MCP Research | Failed 2026-10-22 · agent task failed (no successful call to this server's tools; answer missing ['1706.03762']; no tool result containing ['1706.03762']) |
Dated results
- arXiv MCP passed in ChatGPT (Codex) on 2026-10-15 (Codex CLI 0.162.0-alpha.17.2, package version not recorded, connect time not recorded). Full result
- Hugging Face MCP Server passed in ChatGPT (Codex) on 2026-10-22 (Codex CLI 0.162.0-alpha.17.2, mcp-remote 0.15.2, connect time not recorded). Full result
- Simple arXiv MCP passed in ChatGPT (Codex) on 2026-10-19 (Codex CLI 0.162.0-alpha.17.2, mcp-simple-arxiv 0.6.0, connect time not recorded). Full result
- Paper Search MCP failed in ChatGPT (Codex) on 2026-10-22 (Codex CLI 0.162.0-alpha.17.2, paper-search-mcp 0.1.4, connect time not recorded). Full result
Why arXiv MCP is the candidate
arXiv MCP passed every step in ChatGPT (Codex). It is the group’s site-wide candidate (judged 2026-10-20): Found 'Attention Is All You Need' and returned its arXiv ID (1706.03762) in both Claude Code and Cursor in 2 calls in total, and also passed in ChatGPT (Codex). Simple arXiv MCP passed both with 3 calls. Paper Search MCP failed to start in both clients on Oct 15 (its published uvx command crashes on current dependencies). Zotero MCP needs a local Zotero library and isn't tested. Confirmed Oct 20, 2026: a second run in Claude Code and Cursor passed both tasks again (arxiv-mcp-server 0.8.2).
Provisional: based on one dated run per app (no repeat runs yet), so treat it as a candidate, not a final pick. How we test.
Same servers in all 4 apps
| Server | Claude Code | Cursor | Claude Desktop | ChatGPT (Codex) |
|---|---|---|---|---|
| arXiv MCP Research | Passed 2026-10-20 · install, connect, tools, agent task | Passed 2026-10-20 · install, connect, tools, agent task | Passed 2026-10-18 · install, connect, tools, agent task | Passed 2026-10-15 · install, connect, tools, agent task |
| Hugging Face MCP Server Research | Passed 2026-10-22 · install, connect, tools, agent task | Passed 2026-10-22 · install, connect, tools, agent task | Not tested yet | Passed 2026-10-22 · install, connect, tools, agent task |
| Simple arXiv MCP Research | Passed 2026-10-15 · install, connect, tools, agent task | Passed 2026-10-15 · install, connect, tools, agent task | Passed 2026-10-18 · install, connect, tools, agent task | Passed 2026-10-19 · install, connect, tools, agent task |
| Paper Search MCP Research | Failed 2026-10-15 · did not connect, so the agent task could not use it | Failed 2026-10-15 · did not connect, so the agent task could not use it | Not tested yet | Failed 2026-10-22 · agent task failed (no successful call to this server's tools; answer missing ['1706.03762']; no tool result containing ['1706.03762']) |
What failed or is partial in ChatGPT (Codex)
- Paper Search MCP: failed on 2026-10-22. Recorded reason:
no successful call to this server's tools; answer missing ['1706.03762']; no tool result containing ['1706.03762']
Install in ChatGPT (Codex)
The exact snippet we tested is on the arXiv MCP page (pick the ChatGPT (Codex) tab). Not connecting? ChatGPT (Codex) MCP troubleshooting.
Not tested in ChatGPT (Codex) yet
Perplexity MCP, Gemini Notebook MCP + CLI, Zotero MCP, Korean Law MCP, OpenCity Record, Reyda MCP, Arcmira MCP, Folklore Clinical Variant Interpretation MCP, PredixLab, wordradar MCP, SalesJobs.Now, PaperGraph MCP. Listed from their source; no result in ChatGPT (Codex) yet.
Questions
What is the best research MCP server for ChatGPT (Codex)?
In ToolPassed's hands-on tests in ChatGPT (Codex), arXiv MCP is our provisional candidate for research: it passed install, connect, tools and an agent task on 2026-10-15. We ran 4 research MCP servers in ChatGPT (Codex); 3 passed every step; not a pass: Paper Search MCP (failed).
Does arXiv MCP work with ChatGPT (Codex)?
arXiv MCP passed in ChatGPT (Codex) on 2026-10-15 (Codex CLI 0.162.0-alpha.17.2, package version not recorded, connect time not recorded).
Does Paper Search MCP work with ChatGPT (Codex)?
No, not in our test: Paper Search MCP failed in ChatGPT (Codex) on 2026-10-22 (Codex CLI 0.162.0-alpha.17.2, paper-search-mcp 0.1.4, connect time not recorded). Recorded reason: no successful call to this server's tools; answer missing ['1706.03762']; no tool result containing ['1706.03762']
More: all MCP servers tested in ChatGPT (Codex) · Research in every app · How we test
