What is SineFrame M3?
SineFrame M3 is a pytest-based framework for testing MCP (Model Context Protocol) servers. Instead of checking a server only through a bare model API, it runs the agents your users actually use, such as Claude Code, Codex, OpenCode, or Pi, against your server. Each run records every MCP tool call, so a test can fail when the agent answered from memory and never called your server.
In practice you write ordinary pytest files. Direct tests check schemas, responses, errors, and server state without a model. Agent tests assert which tools a real harness called, with the same tests runnable across several harnesses for side-by-side comparison. You can also pin two versions of a harness to catch regressions after an update, bring your own agent if it speaks the Agent Client Protocol, and run the same suite locally or in CI, where the gate fails when an assertion breaks or when zero tests executed.
Key features
- Runs real Claude Code, Codex, OpenCode, and Pi binaries against an MCP server
- Records and asserts every MCP tool call made by the agent
- Side-by-side comparison of the same tests across multiple harnesses
- Version pinning to detect regressions after a harness update
- Bring-your-own agent via the Agent Client Protocol (ACP)
- CI gate that fails on broken assertions or zero executed tests
Who is it for
- Developers building and maintaining MCP servers
- Teams gating pull requests that change MCP tools
- Engineers who need to verify agent tool-use behavior in CI
Pros and cons
- Tests run against the agent clients users actually run, not a bare model API
- Tests are plain pytest files that live in the user's repo
- Currently in pre-release preview
SineFrame M3 pricing
The vendor does not publish prices in a readable form (often pricing is shown only after signing in).
Is SineFrame M3 free?
The vendor does not state this clearly on the homepage or pricing page.
SineFrame M3 alternatives
| Tool | Price from | Free plan | Category |
|---|---|---|---|
 Agent Skills | not listed | ? | Browser extensions |
 Zapier | od 19,99 USD/mo | yes | Automation |
 n8n | 20 EUR/mo | trial | Automation |
 LochBot | not listed | yes | Browser extensions |
 Browser Use | 0.02 USD | trial | Automation |
 Browserbase | 20 USD/mo | yes | Automation |
All alternatives to SineFrame M3 →
FAQ
What is SineFrame M3 used for?
Pytest framework that tests MCP servers against real coding agents (Claude Code, Codex, OpenCode, Pi) and gates pull requests in CI.
Is SineFrame M3 free?
The vendor does not state this clearly on the homepage or pricing page.
How much does SineFrame M3 cost?
The vendor does not publish prices publicly or requires sign-in.
What are the best SineFrame M3 alternatives?
Closest alternatives: Agent Skills, Zapier, n8n, LochBot, Browser Use.
Data checked October 12, 2026 on the vendor website (m3.sineframe.com).