jev-review-mcp
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@jev-review-mcpreview this diff and tell me if it's safe to merge"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
jev-review-mcp
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Code-review gate as a single-purpose MCP tool, powered by Jev (TypeSafe's System One decision model). One MCP, one job.
Real-world cost on OpenRouter β 4.9M tokens Β· $0.19 over 7 days:
Turns a git diff into a typed decision β no prose, no Jev API knowledge needed from the host agent.
What it does
review_patch(diff, context?) returns a structured verdict instead of free-form text:
Field | Type | Meaning |
|
| Overall call on the patch |
| number (0β1) | P(safe to merge without human review) |
| number (0β4) | Index into the severity scale |
|
| Human-readable severity |
| number (0β1) | Model's calibrated certainty on the verdict |
|
| What the agent should do next |
| boolean | Convenience flag = ( |
Decision gate: action is auto_merge only when verdict === "approve" and safe_prob > 0.8 and confidence >= 0.6. Every other case is human_review.
β οΈ Only execute
auto_mergeon highconfidence. A highsafe_probalone is never permission to merge β gate onconfidence.
Related MCP server: secret-scanner
Install & build
npm install
npm run buildThe compiled server is at dist/index.js.
Add to your MCP client
{
"mcpServers": {
"jev-review": {
"command": "node",
"args": ["/absolute/path/jev-review-mcp/dist/index.js"],
"env": { "TYPESAFE_API_KEY": "ts_xxx" }
}
}
}No key? It still runs in mock mode (JEV_MCP_MOCK=1, or simply no TYPESAFE_API_KEY) so you can try it offline.
Example call
{
"diff": "diff --git a/src/app.ts b/src/app.ts\n- const x = secret\n+ const x = process.env.SECRET",
"context": "Move hardcoded secret to an env var"
}returns something like:
{
"verdict": "request_changes",
"safe_prob": 0.2,
"severity_score": 4,
"severity_label": "critical",
"confidence": 0.7,
"action": "human_review",
"recommended": false
}Model endpoint
Works with any Jev-compatible endpoint. Default is the TypeSafe API
(https://api.typesafe.ai/v1/systemone); override with JEV_BASE_URL
(e.g. an OpenRouter-compatible route) and set TYPESAFE_API_KEY to your
provider key.
Environment variables
Variable | Default | Description |
| β | TypeSafe Jev key. Absent β mock mode |
|
| Set |
|
| Model id sent to the endpoint |
|
| API base URL |
|
| Per-call timeout (ms) |
Mock mode
With no key (or JEV_MCP_MOCK=1) the server answers deterministically from
keyword heuristics β useful for demos, tests, and offline development. A single
derived risk signal drives every field, so the mock stays internally consistent
(risky diff β low safe_prob, high severity, human_review).
Diagnostics
node dist/index.js doctor # human-readable
node dist/index.js doctor --json # machine-readablePrints mock/live mode, key presence, model, and base URL.
Test
npm testRuns a smoke test against the compiled output in deterministic mock mode.
Notes
Jev is a decision model: pure text in β typed decision out. It does not read images or generate prose.
Diffs are truncated at 60k characters to stay within Jev's ~64k-token budget.
Keep the human in the loop: route anything that is not a high-confidence
auto_mergeto a person.
License
MIT
Available Tools
1 toolreview_patchA
Code-review gate powered by Jev (System One decision model). Given a git diff and optional context, returns a verdict (approve / request_changes / needs_discussion), a safety probability, a severity score, a calibrated confidence, and an action (auto_merge / human_review). Only execute auto_merge on high confidence.
| Name | Required | Description | Default |
|---|---|---|---|
| diff | Yes | The git diff or patch to review. | |
| context | No | Optional surrounding context (file purpose, PR description). |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and discloses that this is an AI decision gate returning a verdict, safety probability, severity, confidence, and action. The caution 'Only execute auto_merge on high confidence' implies the tool itself does not execute the merge and warns about the risk, adding behavioral context beyond annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is compact and front-loaded with the core purpose. Every sentence contributes: the first defines the tool, the second lists inputs and outputs, and the third gives a critical safety instruction. There is no filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Because there is no output schema, the description correctly explains all return values (verdict, safety probability, severity score, calibrated confidence, action). It also covers the required and optional inputs and the action condition, making the tool fully invocable by an agent.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description rephrases the inputs ('git diff and optional context') but adds no new detail beyond the schema's own parameter descriptions, so it does not elevate the score.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with 'Code-review gate powered by Jev (System One decision model)', which immediately states the tool's purpose with a specific verb and resource. It then enumerates the exact inputs and outputs, clearly distinguishing this from the sibling screen_content, which is unrelated.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description clearly indicates when to use the tool (given a git diff and optional context) and gives an explicit instruction on how to act on its result: 'Only execute auto_merge on high confidence.' It does not name alternative tools or exclusions, but the only sibling is screen_content, so no routing conflict exists.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
1 tool update
v0.1.0- First observed
review_patch
TDQS
Scored across 1 tool
With only a single tool, there is no possibility of confusion or overlap. The purpose of review_patch is clearly distinct and self-contained.
The sole tool name follows the verb_noun pattern (review_patch), which is clear and predictable. Consistency is trivially maintained with one tool.
A single tool is minimal for a server, though it is focused on one specific gate action. This feels slightly thin but not unreasonable for a narrow purpose.
The domain is a code-review gate, and review_patch covers the core workflow of evaluating a patch and returning a verdict. Missing features like configuration or review history are minor gaps that agents could work around.
Maintenance
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