68efe6970c fix(mcp): JWT on tools/list and REST tools/call server resolution (#28227)
* fix(mcp): JWT on tools/list, REST server_id resolution, tool_server_mismatch

Sign outbound MCP JWTs for list_mcp_tools and inject headers on the tools/list
path. Resolve server_id on /mcp-rest/tools/call and return 403 tool_server_mismatch
when the tool does not belong to the requested server. Default missing arguments to {}.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(mcp): restrict list JWTs to mcp:tools/list and default REST arguments to {}

- List-only JWTs (call_type=list_mcp_tools) no longer carry the broad
  mcp:tools/call scope. _build_scope() now emits only mcp:tools/list
  when no tool name is provided, mirroring the existing least-privilege
  rule that tool-call JWTs omit mcp:tools/list.
- REST /tools/call now defaults a missing 'arguments' field to {} so
  execute_mcp_tool() and downstream **arguments / .keys() calls don't
  receive None and crash with TypeError/AttributeError.

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(mcp): validate tool/server in call_tool; skip JWT signer when not configured or static auth present

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(mcp): align tests and mypy with user_api_key_auth on tools/list

Update mocks for the new _get_tools_from_server parameter, mock server
registry in REST access-denied test, and narrow static_headers for mypy.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(test): accept user_api_key_auth in get_tools_from_mcp_servers mock

The side_effect for the all-servers case did not accept the new kwarg,
so tools/list returned an empty list.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(mcp): fail fast for unknown tools when server mapping exists

Server-name fallback in call_tool must not open an upstream session when
the tool is absent from a populated mapping. Update the HTTP transport test
to register a known tool before asserting not-found behavior.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix mypy

* Fix mypy

* fix(mcp): preserve tools/call scope on missing tool name; pass user_api_key_auth in list_tools

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(mcp): match alias/server_name in _resolve_mcp_server_for_tool_call

The registry lookup in _resolve_mcp_server_for_tool_call previously only
compared candidate.name against the provided server_name, but tool name
prefixes can be derived from a server's alias or server_name (see
get_server_prefix). When the tool→server mapping is empty/stale (cold
start, dynamic tools), the lookup would fail for alias-configured
servers even though get_mcp_server_by_name (used by the REST path)
matches alias, server_name, and name.

Match the same priority of identifiers in both the registry pass and
the unprefixed fallback so the MCP protocol call_tool path is
consistent with the REST path.

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(mcp): reuse proxy_logging DualCache in inject_mcp_jwt_headers_for_upstream

Instead of allocating a fresh DualCache() on every tools/list invocation,
prefer the shared proxy_logging_obj.internal_usage_cache.dual_cache when
available. The cache argument is currently unused by MCPJWTSigner, but
sharing the proxy's cache avoids per-call allocation overhead and matches
the cache identity used elsewhere in the proxy hook plumbing — so any
future per-request state stored in cache will survive across list calls.

Co-authored-by: Claude <noreply@anthropic.com>

* fix(mcp): return 403 ip_filtering for IP-restricted servers in tools/call name lookup

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(test): accept user_api_key_auth kwarg in list_tools mocks

The proxy-infra job was failing on four TestMCPServerManager tests because
the mock_get_tools_from_server stubs did not accept the new
user_api_key_auth keyword argument that list_tools now forwards to
_get_tools_from_server. Add the kwarg to each stub so list_tools can call
through cleanly.

Co-authored-by: Claude <claude@anthropic.com>

* fix(mcp): skip JWT injection when per-user mcp_auth_header is set

MCPClient._get_auth_headers() applies extra_headers AFTER writing
Authorization from auth_value, so an injected JWT silently overwrites
the user's per-server OAuth token. Guard the JWT signer with
'not mcp_auth_header' so per-user OAuth (and any dict-form per-user
auth) takes precedence, mirroring the existing static_headers guard.

Adds a regression test that the signer's inject helper is not called
when mcp_auth_header is supplied.

* fix(mcp): skip JWT injection when extra_headers already has Authorization

When a server uses per-user OAuth tokens, the resolved token is passed
into _get_tools_from_server via extra_headers. The JWT injection guard
only checked mcp_auth_header and the server's static headers, so the
signer would silently overwrite the user's OAuth Authorization header.

Add a check for an existing Authorization entry in extra_headers so
caller-supplied per-user OAuth tokens take precedence over JWT signing.

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* test(mcp): cover JWT signer + tool-call resolution branches

Adds unit tests for the new MCPServerManager helpers (_resolve_mcp_server_for_tool_call,
_resolve_oauth2_headers_for_tool_call) and the new MCPJWTSigner paths
(_build_scope call_type branches and inject_mcp_jwt_headers_for_upstream).
Brings patch coverage above the auto target without changing behavior.

Co-authored-by: Claude <claude@anthropic.com>

* fix(mcp): retry tool-server lookup with prefixed name in REST mismatch check

When the REST /mcp-rest/tools/call path sends a raw tool name plus
requested_server_id, _get_mcp_server_from_tool_name(name) can return
None if the mapping only stores the prefixed form. That bypassed the
tool_server_mismatch 403 guard and let the call fall through to
trusting requested_server.

Retry the lookup with every known prefix of the requested server so
the mismatch check fires whenever the tool is actually registered.

Co-authored-by: Yassin Kortam <yassin@berri.ai>

* fix(mcp): always reject unknown tools in server-name fallback

Defense-in-depth: _resolve_mcp_server_for_tool_call previously skipped
the unknown-tool check whenever the per-server mapping had no entries
yet (cold start, OAuth2 lazy listing, or upstream listing failure),
allowing arbitrary tool names to reach upstream servers.

Tighten the check so the server-name fallback always rejects tool
names not present in the mapping. Callers must call list_tools first
(standard MCP flow) before tools/call can resolve. Removes the
now-unused _mapping_has_tools_for_server helper and adds an
explicit empty-mapping rejection test alongside the existing
populated-mapping rejection test.

Co-authored-by: Sameer Kankute <sameer@berri.ai>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Yassin Kortam <yassin@berri.ai>
Co-authored-by: Claude <claude@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude (greptile subagent) <claude-greptile-bot@anthropic.com>
2026-05-20 13:31:44 -07:00
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2025-11-01 12:58:39 -07:00
2026-05-16 18:31:43 -07:00
2026-05-18 16:27:44 -07:00
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2026-05-19 15:10:37 -07:00

🚅 LiteLLM

LiteLLM AI Gateway

Open Source AI Gateway for 100+ LLMs. Self-hosted. Enterprise-ready. Call any LLM in OpenAI format.

Deploy to Render Deploy on Railway

LiteLLM Proxy Server (AI Gateway) | Hosted Proxy | Enterprise Tier | Website

PyPI Version GitHub Stars Y Combinator W23 Whatsapp Discord Slack CodSpeed

Group 7154 (1)

What is LiteLLM

LiteLLM is an open source AI Gateway that gives you a single, unified interface to call 100+ LLM providers — OpenAI, Anthropic, Gemini, Bedrock, Azure, and more — using the OpenAI format.

Use it as a Python SDK for direct library integration, or deploy the AI Gateway (Proxy Server) as a centralized service for your team or organization.

Jump to LiteLLM Proxy (LLM Gateway) Docs
Jump to Supported LLM Providers


Why LiteLLM

Managing LLM calls across providers gets complicated fast — different SDKs, auth patterns, request formats, and error types for every model. LiteLLM removes that friction:

  • Unified API — one interface for 100+ LLMs, no provider-specific SDK juggling
  • Drop-in OpenAI compatibility — swap providers without rewriting your code
  • Production-ready gateway — virtual keys, spend tracking, guardrails, load balancing, and an admin dashboard out of the box
  • 8ms P95 latency at 1k RPS (benchmarks)

OSS Adopters

Stripe image Google ADK Greptile OpenHands

Netflix

OpenAI Agents SDK

Features

LLMs - Call 100+ LLMs (Python SDK + AI Gateway)

All Supported Endpoints - /chat/completions, /responses, /embeddings, /images, /audio, /batches, /rerank, /a2a, /messages and more.

Python SDK

uv add litellm
from litellm import completion
import os

os.environ["OPENAI_API_KEY"] = "your-openai-key"
os.environ["ANTHROPIC_API_KEY"] = "your-anthropic-key"

# OpenAI
response = completion(model="openai/gpt-4o", messages=[{"role": "user", "content": "Hello!"}])

# Anthropic  
response = completion(model="anthropic/claude-sonnet-4-20250514", messages=[{"role": "user", "content": "Hello!"}])

AI Gateway (Proxy Server)

Getting Started - E2E Tutorial - Setup virtual keys, make your first request

uv tool install 'litellm[proxy]'
litellm --model gpt-4o
import openai

client = openai.OpenAI(api_key="anything", base_url="http://0.0.0.0:4000")
response = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": "Hello!"}]
)

Docs: LLM Providers

Agents - Invoke A2A Agents (Python SDK + AI Gateway)

Supported Providers - LangGraph, Vertex AI Agent Engine, Azure AI Foundry, Bedrock AgentCore, Pydantic AI

Python SDK - A2A Protocol

from litellm.a2a_protocol import A2AClient
from a2a.types import SendMessageRequest, MessageSendParams
from uuid import uuid4

client = A2AClient(base_url="http://localhost:10001")

request = SendMessageRequest(
    id=str(uuid4()),
    params=MessageSendParams(
        message={
            "role": "user",
            "parts": [{"kind": "text", "text": "Hello!"}],
            "messageId": uuid4().hex,
        }
    )
)
response = await client.send_message(request)

AI Gateway (Proxy Server)

Step 1. Add your Agent to the AI Gateway

Step 2. Call Agent via A2A SDK

from a2a.client import A2ACardResolver, A2AClient
from a2a.types import MessageSendParams, SendMessageRequest
from uuid import uuid4
import httpx

base_url = "http://localhost:4000/a2a/my-agent"  # LiteLLM proxy + agent name
headers = {"Authorization": "Bearer sk-1234"}    # LiteLLM Virtual Key

async with httpx.AsyncClient(headers=headers) as httpx_client:
    resolver = A2ACardResolver(httpx_client=httpx_client, base_url=base_url)
    agent_card = await resolver.get_agent_card()
    client = A2AClient(httpx_client=httpx_client, agent_card=agent_card)

    request = SendMessageRequest(
        id=str(uuid4()),
        params=MessageSendParams(
            message={
                "role": "user",
                "parts": [{"kind": "text", "text": "Hello!"}],
                "messageId": uuid4().hex,
            }
        )
    )
    response = await client.send_message(request)

Docs: A2A Agent Gateway

MCP Tools - Connect MCP servers to any LLM (Python SDK + AI Gateway)

Python SDK - MCP Bridge

from mcp import ClientSession, StdioServerParameters
from mcp.client.stdio import stdio_client
from litellm import experimental_mcp_client
import litellm

server_params = StdioServerParameters(command="python", args=["mcp_server.py"])

async with stdio_client(server_params) as (read, write):
    async with ClientSession(read, write) as session:
        await session.initialize()

        # Load MCP tools in OpenAI format
        tools = await experimental_mcp_client.load_mcp_tools(session=session, format="openai")

        # Use with any LiteLLM model
        response = await litellm.acompletion(
            model="gpt-4o",
            messages=[{"role": "user", "content": "What's 3 + 5?"}],
            tools=tools
        )

AI Gateway - MCP Gateway

Step 1. Add your MCP Server to the AI Gateway

Step 2. Call MCP tools via /chat/completions

curl -X POST 'http://0.0.0.0:4000/v1/chat/completions' \
  -H 'Authorization: Bearer sk-1234' \
  -H 'Content-Type: application/json' \
  -d '{
    "model": "gpt-4o",
    "messages": [{"role": "user", "content": "Summarize the latest open PR"}],
    "tools": [{
      "type": "mcp",
      "server_url": "litellm_proxy/mcp/github",
      "server_label": "github_mcp",
      "require_approval": "never"
    }]
  }'

Use with Cursor IDE

{
  "mcpServers": {
    "LiteLLM": {
      "url": "http://localhost:4000/mcp/",
      "headers": {
        "x-litellm-api-key": "Bearer sk-1234"
      }
    }
  }
}

Docs: MCP Gateway

Supported Providers (Website Supported Models | Docs)

Provider /chat/completions /messages /responses /embeddings /image/generations /audio/transcriptions /audio/speech /moderations /batches /rerank
Abliteration (abliteration)
AI/ML API (aiml)
AI21 (ai21)
AI21 Chat (ai21_chat)
Aleph Alpha
Amazon Nova
Anthropic (anthropic)
Anthropic Text (anthropic_text)
Anyscale
AssemblyAI (assemblyai)
Auto Router (auto_router)
AWS - Bedrock (bedrock)
AWS - Sagemaker (sagemaker)
Azure (azure)
Azure AI (azure_ai)
Azure Text (azure_text)
Baseten (baseten)
Bytez (bytez)
Cerebras (cerebras)
Clarifai (clarifai)
Cloudflare AI Workers (cloudflare)
Codestral (codestral)
Cohere (cohere)
Cohere Chat (cohere_chat)
CometAPI (cometapi)
CompactifAI (compactifai)
Custom (custom)
Custom OpenAI (custom_openai)
Dashscope (dashscope)
Databricks (databricks)
DataRobot (datarobot)
Deepgram (deepgram)
DeepInfra (deepinfra)
Deepseek (deepseek)
ElevenLabs (elevenlabs)
Empower (empower)
Fal AI (fal_ai)
Featherless AI (featherless_ai)
Fireworks AI (fireworks_ai)
FriendliAI (friendliai)
Galadriel (galadriel)
GitHub Copilot (github_copilot)
GitHub Models (github)
Google - PaLM
Google - Vertex AI (vertex_ai)
Google AI Studio - Gemini (gemini)
GradientAI (gradient_ai)
Groq AI (groq)
Heroku (heroku)
Hosted VLLM (hosted_vllm)
Huggingface (huggingface)
Hyperbolic (hyperbolic)
IBM - Watsonx.ai (watsonx)
Infinity (infinity)
Jina AI (jina_ai)
Lambda AI (lambda_ai)
Lemonade (lemonade)
LiteLLM Proxy (litellm_proxy)
Llamafile (llamafile)
LM Studio (lm_studio)
Maritalk (maritalk)
Meta - Llama API (meta_llama)
Mistral AI API (mistral)
Moonshot (moonshot)
Morph (morph)
Nebius AI Studio (nebius)
NLP Cloud (nlp_cloud)
Novita AI (novita)
Nscale (nscale)
Nvidia NIM (nvidia_nim)
OCI (oci)
Ollama (ollama)
Ollama Chat (ollama_chat)
Oobabooga (oobabooga)
OpenAI (openai)
OpenAI-like (openai_like)
OpenRouter (openrouter)
OVHCloud AI Endpoints (ovhcloud)
Perplexity AI (perplexity)
Petals (petals)
Predibase (predibase)
Recraft (recraft)
Replicate (replicate)
Sagemaker Chat (sagemaker_chat)
Sambanova (sambanova)
Snowflake (snowflake)
Text Completion Codestral (text-completion-codestral)
Text Completion OpenAI (text-completion-openai)
Together AI (together_ai)
Topaz (topaz)
Triton (triton)
V0 (v0)
Vercel AI Gateway (vercel_ai_gateway)
VLLM (vllm)
Volcengine (volcengine)
Voyage AI (voyage)
WandB Inference (wandb)
Watsonx Text (watsonx_text)
xAI (xai)
Xinference (xinference)

Read the Docs


Get Started

You can use LiteLLM through either the Proxy Server or Python SDK. Both give you a unified interface to access multiple LLMs (100+ LLMs). Choose the option that best fits your needs:

LiteLLM AI Gateway LiteLLM Python SDK
Use Case Central service (LLM Gateway) to access multiple LLMs Use LiteLLM directly in your Python code
Who Uses It? Gen AI Enablement / ML Platform Teams Developers building LLM projects
Key Features Centralized API gateway with authentication and authorization, multi-tenant cost tracking and spend management per project/user, per-project customization (logging, guardrails, caching), virtual keys for secure access control, admin dashboard UI for monitoring and management Direct Python library integration in your codebase, Router with retry/fallback logic across multiple deployments (e.g. Azure/OpenAI) - Router, application-level load balancing and cost tracking, exception handling with OpenAI-compatible errors, observability callbacks (Lunary, MLflow, Langfuse, etc.)

Stable Release: Use docker images with the -stable tag. These have undergone 12 hour load tests, before being published. More information about the release cycle here

Support for more providers. Missing a provider or LLM Platform, raise a feature request.

Run in Developer Mode

Services

  1. Setup .env file in root
  2. Run dependant services docker-compose up db prometheus

Backend

  1. (In root) create virtual environment python -m venv .venv
  2. Activate virtual environment source .venv/bin/activate
  3. Install dependencies uv sync --all-extras --group proxy-dev
  4. uv run prisma generate
  5. prisma generate
  6. Start proxy backend python litellm/proxy/proxy_cli.py

Frontend

  1. Navigate to ui/litellm-dashboard
  2. Install dependencies npm install
  3. Run npm run dev to start the dashboard

Verify Docker Image Signatures

All LiteLLM Docker images published to GHCR are signed with cosign. Every release is signed with the same key introduced in commit 0112e53.

Verify using the pinned commit hash (recommended):

A commit hash is cryptographically immutable, so this is the strongest way to ensure you are using the original signing key:

cosign verify \
  --key https://raw.githubusercontent.com/BerriAI/litellm/0112e53046018d726492c814b3644b7d376029d0/cosign.pub \
  ghcr.io/berriai/litellm:<release-tag>

Verify using a release tag (convenience):

Tags are protected in this repository and resolve to the same key. This option is easier to read but relies on tag protection rules:

cosign verify \
  --key https://raw.githubusercontent.com/BerriAI/litellm/<release-tag>/cosign.pub \
  ghcr.io/berriai/litellm:<release-tag>

Replace <release-tag> with the version you are deploying (e.g. v1.83.0-stable).


Enterprise

For companies that need better security, user management and professional support

Get an Enterprise License Talk to founders

This covers:

  • Features under the LiteLLM Commercial License:
  • Feature Prioritization
  • Custom Integrations
  • Professional Support - Dedicated discord + slack
  • Custom SLAs
  • Secure access with Single Sign-On

Contributing

We welcome contributions to LiteLLM! Whether you're fixing bugs, adding features, or improving documentation, we appreciate your help.

Quick Start for Contributors

This requires uv to be installed.

git clone https://github.com/BerriAI/litellm.git
cd litellm
make install-dev    # Install development dependencies
make format         # Format your code
make lint           # Run all linting checks
make test-unit      # Run unit tests
make format-check   # Check formatting only

For detailed contributing guidelines, see CONTRIBUTING.md.

📖 Contributing to documentation? The LiteLLM docs have moved to a separate repository: BerriAI/litellm-docs. Please open doc PRs there. Docs are served at docs.litellm.ai.

Code Quality / Linting

LiteLLM follows the Google Python Style Guide.

Our automated checks include:

  • Black for code formatting
  • Ruff for linting and code quality
  • MyPy for type checking
  • Circular import detection
  • Import safety checks

All these checks must pass before your PR can be merged.

Support / talk with founders

Contributors

S
Description
Python SDK, Proxy Server (AI Gateway) to call 100+ LLM APIs in OpenAI (or native) format, with cost tracking, guardrails, loadbalancing and logging. [Bedrock, Azure, OpenAI, VertexAI, Cohere, Anthropic, Sagemaker, HuggingFace, VLLM, NVIDIA NIM]
Readme MIT
1.1 GiB
Languages
Python 81%
TypeScript 12.2%
JavaScript 5.9%
HTML 0.5%
HCL 0.2%