Cortex MCP

Multi-level reasoning MCP server with configurable depth levels, session-based state management, structured thought input, and real-time trace resources.

Overview

Cortex MCP is a stdio-only MCP server for stateful, depth-controlled reasoning. The runtime entrypoint in src/index.ts connects createServer() to StdioServerTransport, and the server surface in src/server.ts enables tools, prompts, completions, logging, and subscribable resources around a single session-based reasoning engine.

The live MCP surface confirmed by Inspector is 1 tool, 6 concrete resources, 4 resource templates, and 7 prompts. Sessions are stored in memory, exposed as MCP resources, and cleared on process restart.

Key Features

• reasoning_think supports step-by-step sessions, run_to_completion batches, rollback, early conclusion, and structured observation / hypothesis / evaluation input.
• Four depth levels are built into the engine: basic, normal, high, and expert, each with bounded thought ranges and token budgets.
• Prompt helpers expose reasoning.basic, reasoning.normal, reasoning.high, reasoning.expert, reasoning.continue, reasoning.retry, and get-help.
• Resource endpoints expose internal docs plus live session lists, per-session JSON views, full markdown traces, and individual thought documents.
• Completions are wired for levels, session IDs, and thought names through completable() and resource-template completion hooks.

Requirements

• Node.js >=24 for local npx or npm usage.
• An MCP client that supports stdio transport.
• Optional: Docker if you want to build or run the container image defined by Dockerfile.

Quick Start

Use this standard MCP client configuration:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

Client Configuration

<details> <summary><b>Install in VS Code</b></summary>

Add to .vscode/mcp.json:

{
  "servers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

Or install via CLI:

code --add-mcp '{"name":"cortex-mcp","command":"npx","args":["-y","@j0hanz/cortex-mcp@latest"]}'

For more info, see VS Code MCP docs.

</details>

<details> <summary><b>Install in VS Code Insiders</b></summary>

Add to .vscode/mcp.json:

{
  "servers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

Or install via CLI:

code-insiders --add-mcp '{"name":"cortex-mcp","command":"npx","args":["-y","@j0hanz/cortex-mcp@latest"]}'

For more info, see VS Code Insiders MCP docs.

</details>

<details> <summary><b>Install in Cursor</b></summary>

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Cursor MCP docs.

</details>

<details> <summary><b>Install in Visual Studio</b></summary>

Add to mcp.json (VS integrated):

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Visual Studio MCP docs.

</details>

<details> <summary><b>Install in Goose</b></summary>

Add to Goose extension registry:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Goose MCP docs.

</details>

<details> <summary><b>Install in LM Studio</b></summary>

Add to LM Studio MCP config:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see LM Studio MCP docs.

</details>

<details> <summary><b>Install in Claude Desktop</b></summary>

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Claude Desktop MCP docs.

</details>

<details> <summary><b>Install in Claude Code</b></summary>

Add to Claude Code CLI:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

Or install via CLI:

claude mcp add cortex-mcp -- npx -y @j0hanz/cortex-mcp@latest

For more info, see Claude Code MCP docs.

</details>

<details> <summary><b>Install in Windsurf</b></summary>

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Windsurf MCP docs.

</details>

<details> <summary><b>Install in Amp</b></summary>

Add to Amp MCP config:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

Or install via CLI:

amp mcp add cortex-mcp -- npx -y @j0hanz/cortex-mcp@latest

For more info, see Amp MCP docs.

</details>

<details> <summary><b>Install in Cline</b></summary>

Add to cline_mcp_settings.json:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Cline MCP docs.

</details>

<details> <summary><b>Install in Codex CLI</b></summary>

Add to ~/.codex/config.yaml or codex CLI:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Codex CLI MCP docs.

</details>

<details> <summary><b>Install in GitHub Copilot</b></summary>

Add to .vscode/mcp.json:

{
  "servers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see GitHub Copilot MCP docs.

</details>

<details> <summary><b>Install in Warp</b></summary>

Add to Warp MCP config:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Warp MCP docs.

</details>

<details> <summary><b>Install in Kiro</b></summary>

Add to .kiro/settings/mcp.json:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Kiro MCP docs.

</details>

<details> <summary><b>Install in Gemini CLI</b></summary>

Add to ~/.gemini/settings.json:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Gemini CLI MCP docs.

</details>

<details> <summary><b>Install in Zed</b></summary>

Add to ~/.config/zed/settings.json:

{
  "context_servers": {
    "cortex-mcp": {
      "settings": {
        "command": "npx",
        "args": ["-y", "@j0hanz/cortex-mcp@latest"]
      }
    }
  }
}

For more info, see Zed MCP docs.

</details>

<details> <summary><b>Install in Augment</b></summary>

Add to VS Code settings.json:

Add to your VS Code settings.json under augment.advanced.

{
  "augment.advanced": {
    "mcpServers": [
      {
        "id": "cortex-mcp",
        "command": "npx",
        "args": ["-y", "@j0hanz/cortex-mcp@latest"]
      }
    ]
  }
}

For more info, see Augment MCP docs.

</details>

<details> <summary><b>Install in Roo Code</b></summary>

Add to Roo Code MCP settings:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Roo Code MCP docs.

</details>

<details> <summary><b>Install in Kilo Code</b></summary>

Add to Kilo Code MCP settings:

{
  "mcpServers": {
    "cortex-mcp": {
      "command": "npx",
      "args": ["-y", "@j0hanz/cortex-mcp@latest"]
    }
  }
}

For more info, see Kilo Code MCP docs.

</details>

Use Cases

Start bounded reasoning at the right depth

Use reasoning.basic, reasoning.normal, reasoning.high, or reasoning.expert when the client wants a prompt-first entrypoint, or call reasoning_think directly with query, level, and the first thought. Each response returns the current session state plus a summary string that tells the client how to continue.

Relevant tool: reasoning_think
Related prompts: reasoning.basic, reasoning.normal, reasoning.high, reasoning.expert

Continue, retry, or batch an active session

Reuse sessionId to continue a prior trace, switch to runMode="run_to_completion" when you already have the remaining thought inputs, or use the continuation and retry prompts to generate the next call payload. The handler also supports rollbackToStep and isConclusion for revising or ending a trace early.

Relevant tool: reasoning_think
Related prompts: reasoning.continue, reasoning.retry

Inspect live traces without re-running the tool

Read reasoning://sessions for the active session list, reasoning://sessions/{sessionId} for the JSON detail view, reasoning://sessions/{sessionId}/trace for the markdown transcript, or reasoning://sessions/{sessionId}/thoughts/{thoughtName} for a single thought. This lets a client present progress or audit a session independently from the next tool call.

Relevant resources: reasoning://sessions, reasoning://sessions/{sessionId}, reasoning://sessions/{sessionId}/trace, reasoning://sessions/{sessionId}/thoughts/{thoughtName}

Architecture

[MCP Client]
    |
    | stdio
    v
[src/index.ts]
    createServer()
    -> new StdioServerTransport()
    -> server.connect(transport)
    |
    v
[src/server.ts]
    McpServer("cortex-mcp")
    capabilities:
      - tools
      - prompts
      - completions
      - logging
      - resources { subscribe: true, listChanged: true }
    |
    +--> tools/call
    |     -> reasoning_think
    |     -> src/tools/reasoning-think.ts
    |     -> ReasoningThinkInputSchema / ReasoningThinkToolOutputSchema
    |     -> src/engine/reasoner.ts
    |     -> SessionStore
    |
    +--> prompts/get
    |     -> src/prompts/index.ts
    |
    +--> resources/read
    |     -> src/resources/index.ts
    |     -> internal://* and reasoning://sessions/*
    |
    +--> notifications
          -> logging messages
          -> resources/list_changed
          -> resources/updated
          -> notifications/progress

Request Lifecycle

[Client] -- initialize --> [Server]
[Server] -- serverInfo + capabilities --> [Client]
[Client] -- notifications/initialized --> [Server]
[Client] -- tools/call {name: "reasoning_think", arguments} --> [Handler]
[Handler] -- validate args --> [Reasoner + SessionStore]
[Reasoner] -- progress/resource events --> [Server notifications]
[Handler] -- structuredContent + optional trace resource --> [Client]

MCP Surface

Tools

reasoning_think

Stateful reasoning tool for creating and continuing multi-step sessions. It supports one-step interactive calls, run_to_completion batches, structured observation/hypothesis/evaluation input, rollback, and early conclusion while returning structured session state.

Parameter	Type	Required	Description
query	string	no	Question or problem to analyze.
level	string	no	Depth level. Required for new sessions. basic (1–3 steps, 2K budget), normal (4–8 steps, 8K budget), high (10–15 steps, 32K budget), expert (20–25 steps, 128K budget).
targetThoughts	integer	no	Exact step count. Must fit level range.
sessionId	string	no	Session ID to continue.
runMode	string	no	"step" (default) or "run_to_completion".
thought	any	no	Reasoning text. Stored verbatim. String for step mode, string[] for batch.
isConclusion	boolean	no	End session early at final answer.
rollbackToStep	integer	no	0-based index to rollback to. Discards later thoughts.
stepSummary	string	no	One-sentence step summary.
observation	string	no	Known facts at this step.
hypothesis	string	no	Proposed next idea.
evaluation	string	no	Critique of hypothesis.

<details> <summary>Data Flow</summary>

1. [Client] -- tools/call {name: "reasoning_think", arguments} --> [Server]
   Transport: stdio
2. [Server] -- dispatch("reasoning_think") --> [Handler: src/tools/reasoning-think.ts]
3. [Handler] -- validate(ReasoningThinkInputSchema) --> [src/engine/reasoner.ts]
4. [Reasoner] -- create/update session --> [src/engine/session-store.ts]
5. [Handler] -- structuredContent + optional embedded trace resource --> [Client]

</details>

Resources

Resource	URI or Template	MIME Type	Description
server-instructions	internal://instructions	text/markdown	Usage instructions for the MCP server.
server-config	internal://server-config	application/json	Runtime limits and level configurations for the reasoning server.
tool-catalog	internal://tool-catalog	text/markdown	Tool reference: models, params, outputs, data flow.
tool-info	internal://tool-info/{toolName}	text/markdown	Per-tool contract details.
tool-info-reasoning_think	internal://tool-info/reasoning_think	text/markdown	Contract details for reasoning_think.
workflows	internal://workflows	text/markdown	Recommended workflows and tool sequences.
reasoning.sessions	reasoning://sessions	application/json	List of active reasoning sessions with summaries. Updated in real-time as sessions progress.
reasoning.session	reasoning://sessions/{sessionId}	application/json	Detailed view of a single reasoning session, including all thoughts and metadata.
reasoning.trace	reasoning://sessions/{sessionId}/trace	text/markdown	Markdown trace of a reasoning session (full content).
reasoning.thought	reasoning://sessions/{sessionId}/thoughts/{thoughtName}	text/markdown	Markdown content of a single thought (for example Thought-1).

Prompts

Prompt	Arguments	Description
get-help	none	Return server usage instructions.
reasoning.basic	query required, targetThoughts optional	Basic-depth reasoning (1-3 thoughts).
reasoning.normal	query required, targetThoughts optional	Normal-depth reasoning (4-8 thoughts).
reasoning.high	query required, targetThoughts optional	High-depth reasoning (10-15 thoughts).
reasoning.expert	query required, targetThoughts optional	Expert-depth reasoning (20-25 thoughts).
reasoning.continue	sessionId required, query optional, level optional	Continue an existing session. Optional follow-up query.
reasoning.retry	query required, level required, targetThoughts optional	Retry a failed reasoning task with modified parameters.

MCP Capabilities

Capability	Status	Evidence
tools	confirmed	src/server.ts:203-205, src/tools/reasoning-think.ts:479
prompts	confirmed	src/server.ts:205, src/prompts/index.ts:201
completions	confirmed	src/server.ts:207, src/prompts/index.ts:249, src/resources/index.ts:375
logging	confirmed	src/server.ts:204, src/server.ts:98
resources.subscribe	confirmed	src/server.ts:208, src/server.ts:121
resources.listChanged	confirmed	src/server.ts:208, src/server.ts:114
progress notifications	confirmed	src/lib/mcp.ts:71, src/tools/reasoning-think.ts:424

Tool Annotations

Annotation	Value	Evidence
readOnlyHint	false	src/tools/reasoning-think.ts:500
destructiveHint	false	src/tools/reasoning-think.ts:502
openWorldHint	false	src/tools/reasoning-think.ts:503
idempotentHint	false	src/tools/reasoning-think.ts:501

Structured Output

• reasoning_think declares outputSchema and returns structuredContent, with an embedded trace resource when the trace is small enough. Evidence: src/tools/reasoning-think.ts:498, src/lib/mcp.ts:97-114.

Configuration

Variable	Default	Required	Evidence
CORTEX_SESSION_TTL_MS	1800000 (30 minutes)	no	src/engine/reasoner.ts:22, src/engine/session-store.ts:19
CORTEX_MAX_SESSIONS	100	no	src/engine/reasoner.ts:23, src/engine/session-store.ts:20
CORTEX_MAX_TOTAL_TOKENS	2000000	no	src/engine/reasoner.ts:24, src/engine/session-store.ts:21
CORTEX_MAX_ACTIVE_REASONING_TASKS	32	no	src/engine/config.ts:41-44
CORTEX_REDACT_TRACE_CONTENT	false	no	src/engine/config.ts:21

[!NOTE] The source does not define any HTTP host/port configuration. The only other environment-related signal is NODE_ENV=production in the Docker image and --env-file=.env in the local dev:run script.

Security

Control	Status	Evidence
input validation	confirmed	src/schemas/inputs.ts:13, src/schemas/outputs.ts:46, src/prompts/index.ts:207
stdout-safe logging fallback	confirmed	src/server.ts:98, src/server.ts:145
main-thread-only runtime	confirmed	src/index.ts:15-25
non-root container user	confirmed	Dockerfile:37

[!NOTE] No auth, OAuth, HTTP origin checks, or rate-limiting controls are implemented in the current source because the server only exposes stdio transport.

Development

Script	Command	Purpose
dev	tsc --watch --preserveWatchOutput	Watch and compile source during development.
dev:run	node --env-file=.env --watch dist/index.js	Run the built server in watch mode with an optional local .env file.
build	node scripts/tasks.mjs build	Clean dist, compile TypeScript, copy assets, and make the entrypoint executable.
lint	eslint .	Run ESLint across the repository.
type-check	node scripts/tasks.mjs type-check	Run source and test TypeScript checks concurrently.
test	node scripts/tasks.mjs test	Run the TypeScript test suites with the configured loader.
test:dist	node scripts/tasks.mjs test:dist	Rebuild first, then run tests against the built output.
test:fast	node --test --import tsx/esm src/__tests__/**/*.test.ts node-tests/**/*.test.ts	Run the fast direct test command without the task wrapper.
format	prettier --write .	Format the repository.
inspector	npm run build && npx -y @modelcontextprotocol/inspector node dist/index.js	Build the server and open it in the MCP Inspector.
prepublishOnly	npm run lint && npm run type-check && npm run build	Enforce release checks before publishing.

Additional helper scripts for diagnostics, coverage, asset copying, and knip are defined in package.json.

Build and Release

• .github/workflows/release.yml bumps package.json and server.json, then runs npm run lint, npm run type-check, npm run test, and npm run build before tagging and creating a GitHub release.
• The same workflow publishes the package to npm with Trusted Publishing, publishes to the MCP Registry with mcp-publisher, and pushes a multi-arch Docker image to ghcr.io.
• Dockerfile uses a multi-stage Node 24 Alpine build, prunes dev dependencies, and runs the released container as the mcp user.

Troubleshooting

• Sessions are in memory and expire after 30 minutes by default. If you receive E_SESSION_NOT_FOUND, start a new session or increase CORTEX_SESSION_TTL_MS.
• runMode="run_to_completion" requires enough thought entries to cover the remaining steps. If you want the server to return after each step, keep the default step mode.
• For stdio transport, do not add custom stdout logging around the server process. This server routes logs through MCP logging and falls back to stderr on failures.

Credits

Dependency	Registry
@modelcontextprotocol/sdk	npm
zod	npm

Contributing and License

• License: MIT
• Contributions are welcome via pull requests.