langchainjs-mcp-adapters

Provides LangChain.js adapters to integrate Model Context Protocol (MCP) tools into LangChain.js applications, supporting MCP tool usage over stdio and SSE transports via the @modelcontextprotocol/sdk dependency.

Evaluated Mar 30, 2026 (21d ago)

Repo ↗ DevTools langchain langchainjs mcp model-context-protocol typescript agent-tools ai-tools sse stdio

⚙ Agent Friendliness

/ 100

Can an agent use this?

🔒 Security

/ 100

Is it safe for agents?

⚡ Reliability

/ 100

Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality

Documentation

Error Messages

Auth Simplicity

Rate Limits

🔒 Security

TLS Enforcement

Auth Strength

Scope Granularity

Dep. Hygiene

Secret Handling

As a client-side adapter/library, it likely inherits transport security and auth behavior from the MCP server and @modelcontextprotocol/sdk. The provided materials do not mention auth, secrets handling, or TLS requirements directly.

⚡ Reliability

Uptime/SLA

Version Stability

Breaking Changes

Error Recovery

Best When

You want to connect LangChain.js agents to MCP tool servers and you already operate (or can operate) an MCP server using stdio or SSE transports.

Avoid When

You need a turnkey hosted service with built-in auth, billing, and operational guarantees instead of a library adapter.

Use Cases

• Use MCP tool servers from within LangChain.js agent workflows
• Bridge existing MCP tool ecosystems into LangChain.js tool calling
• Run MCP tools over stdio or SSE in a Node.js/TypeScript LangChain application

Not For

• Directly exposing a public REST/GraphQL/gRPC API to end users
• Handling authentication/authorization for your MCP tools server (this adapter is a client-side wrapper)
• Implementing large-scale tool orchestration without considering MCP server availability and transport behavior

Interface

REST API

GraphQL

gRPC

MCP Server

SDK

Yes

Webhooks

Authentication

Methods: Depends on MCP transport/server configuration (not evidenced in provided README/manifest)

OAuth: No Scopes: No

No authentication mechanism is described in the provided README/manifest; any auth is likely handled by the MCP server/transport layer outside this wrapper.

Pricing

Free tier: No

Requires CC: No

Open-source npm package (MIT) per repository metadata; costs are operational (running MCP servers/LLMs) rather than subscription by this package.

Agent Metadata

Pagination

none

Idempotent

False

Retry Guidance

Not documented

Known Gotchas

⚠ Adapter migration: repository indicates the package moved into the LangChainJS monorepo; consumers may need to update import paths/version alignment.
⚠ Transport-specific behavior: stdio vs SSE can affect lifecycle and error/reconnect semantics; agent retry strategies may vary accordingly.
⚠ This adapter likely does not enforce tool-level auth/authorization; misconfigured MCP server permissions could surface as tool call failures.

Alternatives

Use @modelcontextprotocol/sdk directly with custom LangChain.js tool wrappers LangChain.js monorepo’s moved-in libs/langchain-mcp-adapters implementation Other MCP-to-framework adapters if available for your stack

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API endpoint ↗ Agent guide ↗ Report inaccuracy

Scores are editorial opinions as of 2026-03-30.