🌏 中文版
Version Info
| Item | Value |
|---|---|
| Framework | Agno |
| Version | v3.0.6 |
| Previous | v3.0.5 |
| Release Date | 2026-09-04 |
| Release Notes | GitHub Release |
| GitHub | agno-agi/agno |
| Stars | 42.0k |
Why This Release Matters
The previous entry (3.0.5) fixed Knowledge ingestion's data-integrity contract. 3.0.6 goes back to fix the deployment model of MCP serving itself. Until now, MCP servers — including Agno's own AgentOS MCP endpoint — defaulted to session-based: once a client connects, its session state is pinned to a specific process, so scaling to multiple replicas meant either routing every request from the same client to the same machine via session affinity, or building your own session-sharing layer. 3.0.6 adds MCPConfig(stateless=True), which serves /mcp without tracking session state at all — any replica can answer any request. That means horizontally scaling an MCP server can finally look like any stateless HTTP API behind a load balancer, with no sticky routing required. The same release also teaches MCPTools to negotiate the MCP protocol version (protocol_mode="auto"), following the sessionless negotiation capability added in this year's 2026-07-28 spec, connecting the client-side and server-side statelessness together.
Key Changes
- Stateless MCP serving:
MCPConfig(stateless=True)serves/mcpwithout session tracking, so any replica can answer any request and multi-instance deployments no longer need session affinity → the cost is losing server-initiated notifications and SSE resumability, so it's off by default — deployments that need horizontal scaling can weigh the tradeoff and opt in MCPTools(protocol_mode=...)protocol negotiation: defaults to"legacy", preserving today's session-based behavior unchanged;"auto"negotiates the newest protocol era both sides support (sessionless capability comes from the MCP2026-07-28spec) → existing servers are unaffected and still accept the legacy handshake; MCP clients are now built internally onfastmcp.Client- AgentOS MCP Server Card: a new
GET /mcp/server-cardendpoint lists the currently served tools and carries a configurable name, version, and instructions → lets a client self-discover what an AgentOS instance offers .zip/.emlfile uploads: AgentOS now supports uploading and unpacking these archive formatsAuthorizationConfig.excluded_route_paths: marks specific custom routes as public without disabling auth globally- Bedrock custom async client: models and embedders can now be passed a caller-supplied async client
- Several stability fixes: Anthropic now replays prior assistant turns verbatim so thinking blocks stop getting rejected; Gemini resolves the actual image MIME type instead of hard-coding
image/jpeg;RecursiveChunkingno longer emits duplicate trailing chunks; AG-UI now sends wire fields instead of the wholeRunContextto remote entities and exposes streamed run errors
Breaking Changes
No breaking changes in this release. Both stateless=True and protocol_mode="auto" are opt-in — the defaults preserve today's session-based behavior.
Upgrade directly, no code changes required.
Migration Guide
pip install --upgrade agno==3.0.6To let AgentOS's MCP endpoint support multi-replica deployment, enable stateless serving:
from agno.os.mcp import MCPConfig
mcp_config = MCPConfig(stateless=True)
# /mcp can now sit behind a plain load balancer, no session affinity needed
# Tradeoff: no server-initiated notifications or SSE resumabilityTo let the MCP client auto-negotiate the newest protocol version:
from agno.tools.mcp import MCPTools
mcp_tools = MCPTools(
url="https://example.com/mcp",
protocol_mode="auto", # defaults to "legacy"
)How It Compares to Other Frameworks
The MCP spec only formalized sessionless negotiation earlier this year (2026-07-28), and Agno 3.0.6 implements it on both the client and server side almost immediately — consistent with Agno treating "absorb the newest MCP ecosystem capabilities fast" as a core selling point, in line with its #1 Agentic Index ranking and multi-model-flexibility positioning. By comparison, LangGraph and CrewAI don't yet support MCP protocol version negotiation at this level of granularity, giving Agno a temporary lead on the path to MCP-native production deployment.
Today's Takeaway
I used to assume MCP servers inherently needed session affinity to scale horizontally. Seeing Agno add stateless=True at the protocol level made it clear that session-based design was just an early implementation default, not a hard constraint of the protocol — as long as you're willing to give up features like server-initiated notifications that need a long-lived connection state, an MCP server can scale just as easily as a plain stateless REST API. Evaluating an Agent framework's MCP support should look beyond how many tools it wires up, to whether it has designed multi-replica deployment into the protocol layer itself.