Evidra — Fitness Decision Engine

Your AI assistant is the coach's brain and voice. Evidra is the exercise science and safety engine behind it.

Evidra is an MCP server. It turns the evidence you already have into a training decision — not advice invented from nothing, but a from → to change against the session already on your calendar, with the evidence and the rule behind it.

It runs on your own machine, and it does not retain your evidence.

Where this is

The current release is v0.3.3. v0.1.0 was the first public release.

The decision logic is covered by a deterministic test and evaluation suite: under the same version of Evidra, the same evidence produces the same decision, and every decision cites the evidence and the rule behind it. It has not yet been validated over extended real-world training blocks.

You supply the evidence. Evidra does not connect to Apple Health, Garmin, Strava, or any other service on your behalf, and it is not waiting for you to link an account. It reads what you or your assistant hand it in the call — which can be as ordinary as saying what you trained yesterday and how you slept. If you already have exported data from those services, Evidra can evaluate that as input as well.

Signals you do not supply are reported in signalCoverage and lower the decision's confidence. They are never filled in with defaults.

Decision, not recommendation

This distinction is the whole product.

A general-purpose model can produce the left column. It cannot produce the right one, because the right one needs your plan, your recent load, and this morning's recovery — and then needs the arithmetic done the same way every time.

Every decision comes back in five layers:

Evidence → Fitness State → Decision (intent) → Action (from → to) → Reason (bound to evidence)

Decision types: keep (keeping the session is also a decision) · adjust · substitute · defer · advance

Intent and action are kept separate on purpose: the same intent becomes a different action depending on your equipment, your schedule, and your injuries.

How the work is divided

Evidra calls no model to produce a decision. Under the same version of Evidra, identical inputs produce an identical decision, and every number is traceable. The language you read is your assistant's; the judgment is arithmetic.

Tools

Any single source works

You do not need to own a Garmin, an Apple Watch, and a Strava subscription.

• A runner with only Strava gets decisions from training load.
• Someone who doesn't wear a watch to bed gets decisions from HRV and their vendor's composite score.
• Someone who just says it out loud — "ran 45 minutes yesterday, slept about seven hours" — gets a decision from that.

This is the design, not a degraded mode. Every response reports which signals it had:

"signalCoverage": {
  "recovery": { "usable": ["hrv"], "missing": ["sleep"] },
  "training": { "usable": ["trainingLoad"], "missing": [] }
}

• recovery.missing — no fresh reading today for sleep, HRV, resting heart rate, or stress
• training.missing — a session in the last 7 days arrived without a load figure

Missing inputs are never filled in with defaults. No RPE means no RPE, not 5. What's missing is reported and confidence drops accordingly. A session without a load figure is not counted as zero fatigue, because nobody said it was easy — it's reported as missing instead, and training.missing is how you find out.

Privacy Policy

Evidra runs locally and does not retain your evidence.

We process only the minimum health-related evidence submitted by the caller, solely to compute the requested fitness decision. We do not retain, sell, use for training, or use it for unrelated purposes.

As a desktop extension, this is checkable against the compiled server it ships: Evidra itself performs no outbound network requests, does not persist your evidence, and has no runtime dependencies, telemetry, model calls, or accounts. Evidence exists in memory for the duration of one tool call.

Full policy: PRIVACY.md

Evidra is not a medical device and does not provide medical advice. It is intended for general fitness and training purposes only.

Install

Evidra ships as a Claude Desktop extension (.mcpb).

1. Download the latest evidra.mcpb from Releases
2. Open Claude Desktop → Settings → Extensions
3. Install the .mcpb file
4. Ask a question that needs a decision — for example, "I've got VO₂max intervals scheduled today. Am I in shape for them?"

Requires Node.js 20 or newer.

An extension is a copy taken at install time. After installing a new version, restart Claude Desktop completely — closing the window is not enough.

Availability

Support

Bug reports and questions: open an issue

Privacy requests, or anything you would rather not post publicly: evidramcp@icloud.com

License

Proprietary — see LICENSE. You may install and run Evidra for your own use. Copying, modifying, and redistributing it are not permitted.