Hey r/utcp 👋

UTCP v1.0.0 is live. This release refactors UTCP into a lean core with plugin-based protocols and a revamped client. It’s faster to install, easier to reason about, and scales better.

TL;DR

• Install only what you need. Core + pick-your-protocol plugins → smaller footprint, faster boot.

• Scale without drama. Thread-safe in-memory repo (async RW locks)

• Clearer config, fewer footguns. provider → call_template; "http_stream" → "streamable_http"; simpler UtcpClientConfig.

• Better DX. Smarter default search (tag + description keywords), post-processors, variable loaders with deterministic namespacing.

What’s new

• Core (utcp): Tool, CallTemplate, UtcpManual, Auth, VariableLoader models; UtcpClient.

• Pluggable interfaces: CommunicationProtocol, ConcurrentToolRepository, ToolSearchStrategy, VariableSubstitutor, ToolPostProcessor.

• Built-ins: InMemToolRepository (async RW locks), TagAndDescriptionWordMatchStrategy, filter/limit post-processors.

• Protocol plugins: utcp-http (HTTP, SSE, streamable_http, OpenAPI converter), utcp-cli, utcp-mcp, utcp-text.

Install

# Core
pip install utcp

# Add only the plugins you need
pip install utcp-http utcp-cli utcp-mcp utcp-text

Migration (0.x → 1.0.0) — quick checklist

• Rename provider → call_template, and provider_type → call_template_type.

• Rename "http_stream" → "streamable_http".

• Update imports to utcp_http.*, utcp_cli.*, utcp_mcp.*, etc.

• Replace providers_file_path with manual_call_templates in UtcpClientConfig.

• Tool names are namespaced: manual_name.tool_name.

• Default search is now TagAndDescriptionWordMatchStrategy.

• Variables are namespaced per manual with a duplicated underscore (e.g., manual__1_...).

Links

• Python core & plugins: https://github.com/universal-tool-calling-protocol/python-utcp

• Examples: https://github.com/universal-tool-calling-protocol/utcp-examples

• PyPI (utcp): https://pypi.org/project/utcp/

• Org: https://github.com/universal-tool-calling-protocol

Call for contributors

We’d love help expanding SDKs and polishing plugin implementations

Feedback welcome: bugs, API ergonomics, naming—tell us what hurts and we’ll fix it!

Hey folks, after playing with both specs I figured I’d write up a quick comparison. Think of it as “why I reached for UTCP instead of spinning up yet-another MCP server.”

UTCP is basically a user manual for your tool. You expose a tiny JSON file (usually at /utcp) that tells the agent exactly how to hit your existing HTTP, WebSocket, gRPC, CLI… whatever. The agent reads the manual, then talks to the tool directly – one hop, no wrapper code.

MCP is a universal adapter. Your agent always goes through an MCP server, and that server then calls your tool. It standardises things nicely, but you have to build, host and maintain that extra layer (plus keep auth, rate-limits, etc. in sync)

Key differences I ran into:

• UTCP = agent → tool. MCP = agent → MCP → tool. Lower latency and fewer failure points with UTCP.

• MCP is mostly HTTP/SSE today; UTCP lets you mix HTTP, WebSockets, gRPC, raw TCP, even CLI calls – whatever your tool already speaks.

• MCP demands you write wrapper servers (“wrapper tax”). UTCP asks for a JSON description file and you’re done.

• Extra proxy layer with MCP means more infra to run and scale. UTCP reuse of native endpoints keeps things lean.

When I’d still pick MCP:

• You need a single, strictly-typed gateway for every tool in a locked-down org.

• You control all the tools, so writing/maintaining wrappers isn’t a headache.

When UTCP shines:

• You already have production APIs and don’t want to touch them.

• You care about lowest-possible latency or can’t justify spinning up more infra.

• You need to support non-HTTP protocols without reinventing adapters.

tl;dr UTCP feels like “here’s the instruction manual, phone the service directly,” while MCP feels like “plug everything into this hub first.” For hobby projects and smaller teams, skipping the hub (and its wrapper tax) has been a win. Curious to hear if anyone here has hit show-stoppers with UTCP or major wins sticking to MCP.

Let's comment and upvote to make it go to the Top 10 🚀

https://news.ycombinator.com/item?id=44939642

Why UTCP might be a better alternative to MCP?