Hermes MCP
A comprehensive Elixir/OTP implementation of the Model Context Protocol providing both client and server functionality, leveraging Elixir's concurrency model and fault tolerance for building robust MCP integrations in Phoenix and standalone applications.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Message/event bus MCP server. Auth depends on underlying message broker. Use broker-level auth (AMQP credentials, Kafka SASL). TLS for transport.
⚡ Reliability
Best When
You are building MCP infrastructure in an Elixir/Phoenix application and need production-grade concurrency, fault tolerance, and hot code reloading.
Avoid When
Your team does not have Elixir expertise — the learning curve plus MCP complexity is significant for non-Elixir shops.
Use Cases
- • Building MCP servers in Elixir/Phoenix applications that expose custom tools to AI assistants
- • Creating MCP clients in Elixir to connect to and interact with existing MCP servers
- • Running high-concurrency, fault-tolerant MCP infrastructure where OTP supervision trees provide resilience
Not For
- • Teams not using Elixir/Erlang — this SDK is Elixir-specific
- • Rapid prototyping where Python or TypeScript MCP SDKs have more examples and community resources
- • Simple single-tool integrations where the full OTP supervision model adds unnecessary complexity
Interface
Authentication
Auth is handled at the transport layer (HTTP/SSE). The SDK itself does not prescribe an auth mechanism; implementors add auth via Plug/Phoenix middleware.
Pricing
MIT licensed. Available on Hex.pm. Maintained by CloudWalk.
Agent Metadata
Known Gotchas
- ⚠ Elixir ecosystem familiarity required — Mix, OTP, and supervision trees are prerequisites
- ⚠ 44 releases in relatively short history suggests active API evolution — pin versions carefully
- ⚠ Smaller community than Python/TypeScript MCP SDKs means fewer examples and Stack Overflow answers
- ⚠ Transport selection (stdio vs SSE vs streamable HTTP) requires explicit configuration that affects deployment topology
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Hermes MCP.
Scores are editorial opinions as of 2026-03-06.