# Nylas Codex MCP Evaluation

**Category:** Email
**Score:** 49 (D)

This is the agent-readable Devtool Arena evaluation page for Nylas on Codex MCP.

## Summary

| Metric | Value |
|--------|-------|
| Status | completed |
| Overall score | 49 |
| Grade | D |
| Eval score | 47 |
| Discovery score | 55 |
| Cost | $0.13 |
| Runtime | 4m 10s |
| Tool calls | 6 |
| Errors | 0 |
| Tokens used | 434815 |
| Success | No |

## Agent-Readiness Checklist

| Signal | Evidence |
|--------|----------|
| Context7 | Not found |
| llms.txt | Not found |
| MCP server | Not found |
| Typed SDK | Not found |
| OpenAPI | Not found |
| Agent skills | Not found |
| CLI | Not found |

## Evaluation Prompt

````text

# Task
Using the Nylas MCP, perform email operations:

1. Discover available MCP tools and their capabilities
2. Create a new email inbox (or list available inboxes/domains)
3. Send an email with subject "Hello from [REDACTED:ORG] MCP Leaderboard" and body "This is a ***** email sent via the Nylas MCP server." (If the recipient is blocked, send to any available address instead.)
4. List messages or check email status
5. Print all output as JSON

Use ONLY the MCP tools for all operations.

You MUST use the Nylas MCP server to accomplish this task.
Use the MCP tools for the actual product operations. Do NOT use curl, fetch, raw HTTP requests, CLI commands, or SDK calls as substitutes.

Use the MCP tools' help/descriptions to understand what each tool does.
If you need additional context, check the documentation: https://developer.nylas.com/docs/dev-guide/mcp/

## Setup
Do NOT assume the Nylas MCP server is already installed or already running in this sandbox.
Review the installation and authentication details below before starting the task.

### Installation
Transport: `http`
This MCP server uses `http` transport.
Codex should connect to: `https://mcp.us.nylas.com`
Do not assume a local MCP package is already installed; the task depends on the remote server being reachable.
Bootstrap notes: Nylas documents this exact URL and bearer_token_env_var in its Codex MCP configuration. The server is remote; no package installation or local launch command is needed. NYLAS_CLIENT_ID is present in the sandbox but is not required by Nylas's documented API-key MCP configuration. The URL is the US endpoint. Use the EU endpoint only if the Nylas account is in the EU region.

### Authentication
The following environment variables are already set in this environment: `NYLAS_API_KEY`
The MCP server should read them automatically when it starts.

## Execution
1. The harness has already written the launch configuration for `nylas`. Start with the task directly; do not rewrite agent settings, `.mcp-runtime.json`, or build a separate MCP client unless the connected server still fails after a normal retry.
2. You do not need to enumerate every MCP tool up front; inspect only the relevant tools you need. Agent-facing MCP tool names may be namespaced like `mcp__nylas__<tool_name>`.
3. Complete the task described above using MCP tools for the actual product operations.
4. If the server fails to start or authenticate, debug the documented setup and retry. Do not fall back to raw HTTP, SDK, CLI, or manual JSON-RPC/MCP calls as a substitute for exposed MCP tools.

Work in the /home/daytona/app directory.
If you use Bash during setup or debugging, limit it to installation/configuration work and then return to MCP tools for the task itself.
If there are errors, debug and fix them until the task runs successfully.

## Summary
When you are done, write a JSON summary file to /home/daytona/app/results.json with this structure:
{
  "operations": [
    {"step": 1, "description": "What you did", "mcp_tool": "tool_name", "success": true/false, "output_summary": "brief result"},
    ...
  ],
  "overall_success": true/false,
  "notes": ["any relevant notes about the execution"]
}

````

## Grader Results

| Check | Passed | Weight | Score | Details |
|-------|--------|--------|-------|---------|
| Task | No | — | — | — |
| Llms Txt | Yes | — | 10 | — |
| Tool Count | Yes | — | 10 | — |
| Auth Method | Yes | — | 15 | — |
| Official Mcp | Yes | — | 5 | — |
| Output Schema | No | — | 0 | — |
| Tool Stability | Yes | — | 5 | — |
| Tool Description Length | Yes | — | 10 | — |

## Run Artifacts

| Artifact | Value |
|----------|-------|
| Conversation turns | 10 |
| Tool call traces | 6 |
| Generated files | 1 |
| Exit code | — |
| Completed at | 2026-09-27T14:45:20.77598+00:00 |

### Generated Files

- /home/daytona/app/results.json

## Related Pages

- [Codex MCP leaderboard](/leaderboard/codex/mcp)
- [Compare Codex MCP companies](/leaderboard/codex/mcp/compare)
- [Agent Landscape](/leaderboard/discoverability)

Canonical URL: https://devtoolarena.com/codex/mcp/nylas