Jev Tools MCP Server

jev-agent-tools

Six evidence-oriented tools for pi, omp and any MCP client, compatible with the Jev API format. Use them to navigate unfamiliar code, ask typed questions about repository evidence, review completed changes and select existing tests. They complement reading, searching and execution; they do not replace them.

Watch the launch video (74 s, MP4).

Install

Install through your host's package manager, or register the MCP server with an MCP client. The npm package is jev-agent-tools. pi and omp load its TypeScript sources directly; the MCP server ships prebuilt.

pi

pi install npm:jev-agent-tools@0.2.0
# Project-local installation:
pi install -l npm:jev-agent-tools@0.2.0

omp

omp plugin install jev-agent-tools@0.2.0

Any MCP client

Since version 0.2.0, the package also ships jev-agent-tools-mcp, a stdio MCP server that exposes the same six tools to any MCP client: Claude Code, Claude Desktop, Kiro, Cursor, VS Code, Codex CLI and others. A typical mcpServers entry:

{
  "mcpServers": {
    "jev": {
      "command": "npx",
      "args": ["-y", "-p", "jev-agent-tools", "jev-agent-tools-mcp", "--root", "/path/to/repository"],
      "env": {
        "JEV_TOOLS_URL": "${JEV_TOOLS_URL}",
        "JEV_TOOLS_API_KEY": "${JEV_TOOLS_API_KEY}"
      }
    }
  }
}

On Windows most clients start commands without a shell, so use "command": "cmd" with "/c", "npx" at the start of args. The MCP setup guide has per-client files, CLI commands, variable interpolation, verification and troubleshooting. Releases are also listed in the official MCP Registry as io.github.NomenAK/jev-agent-tools. Add the agent instructions to CLAUDE.md, AGENTS.md or a Kiro steering file so the agent uses and reads the tools correctly.

The server reads the same environment variables as pi and omp and the configuration saved by /jev-setup. One server process is one session. The automatic run-end documentation check does not exist in MCP; call jev_check_diff with check: "docs" instead. jev_ask is marked as not read-only while commands are enabled; set JEV_TOOLS_ALLOW_COMMAND=0 to remove command from its schema.

Requirements and compatibility

Requires Node.js 24 or later. Supported host baselines are pi 0.87.1 and omp 18.4.10. These are support baselines, not claims that every later version has been individually validated. omp uses its Bun runtime; Node.js is also required for Node-based project checks. Git and, for optional command evidence, Bash must be available. On Windows, command evidence uses Git for Windows bash (found next to git on PATH or under Program Files); the WSL bash.exe launchers are never used. Set JEV_TOOLS_BASH to the full path of another bash. Optional native parsers and file-search acceleration may be unavailable on some platforms; affected tools report their limitations.

The published jev-agent-tools@0.1.3 package was also checked with pi 1.0.0 on Linux under Node.js 24.15.0: npm installation, TypeScript checking against the host types, all six tools in the actual CLI, and reading-guide injection passed. The CLI smoke used a simulated conversation provider and Jev endpoint; it verifies host integration, not live model accuracy or every tool scenario.

pi 1.0.0 packaging warning: the package declares @sinclair/typebox in dependencies, while pi expects host-provided extension modules in peerDependencies with a "*" range. pi warns that separately installed copies can create duplicate runtime modules. The warning did not prevent the smoke from completing; it remains a packaging issue, not a claim of warning-free compatibility.

Configure

Interactive setup

In the main interactive terminal of pi or omp, a first launch without configuration offers Configure now / Later. Run /jev-setup at any time to change the endpoint, model or key. The key is typed in a masked field and is never passed as a command-line argument. Choose This session only (nothing is written) or Save for future sessions. Cancelling at any step changes nothing.

No dialog appears in print, JSON or RPC modes, or in sub-agents; configure those with the environment variables below. Changes apply immediately, without restarting the host.

Interactive setup waits for submission or cancellation, without a credential-entry timeout. The first-launch offer does not keep the host's startup event handler open while you find the endpoint or key.

Precedence per field: environment variable, then launch flag, then this session's setup, then saved configuration, then the default model openjev. A field set by the environment or a flag is shown as controlled and is never saved.

Saved configuration lives outside the repository at $XDG_CONFIG_HOME/jev-agent-tools/config.json (default ~/.config/jev-agent-tools/config.json), in a private directory (0700) with a private file (0600). On Windows, where mode bits do not exist, privacy is the folder's access list: saving restricts it to you, SYSTEM and Administrators, and loading refuses any other account with access. The key is stored in plaintext, not encrypted. Storage that is a symlink, accessible to other users, not owned by you or malformed is refused rather than overwritten. The MCP server also reads this file, after environment variables.

Environment variables

Set these before starting the host, using your own endpoint and credentials:

export JEV_TOOLS_URL="${YOUR_JEV_ENDPOINT}"
export JEV_TOOLS_API_KEY="${YOUR_JEV_API_KEY}"
# Optional; already the default:
export JEV_TOOLS_MODEL="openjev"

YOUR_* placeholders are inputs you supply, not additional product settings. Environment variables are read when the extension loads and take precedence over everything else.

Without the endpoint or key, tools remain registered and explain the missing configuration; the automatic documentation check is disabled. There is no fallback to a chat model. Per-tool max_calls is separate from session limits. A model name echoed by the response does not establish which model was actually served.

Choose a tool

Use native read/search tools or code for exact source text, known symbols, filenames, line numbers, counts and arithmetic. Run commands yourself when you need their full output. Tool reference examples use fictional repository paths and are illustrative calls, not recorded executions.

Read the results

A line without a mark is a verdict: a lead to check before editing, deleting or reporting completion, not a proof. Probabilities concern the evidence shown, not everything in your repository.

Ordinary boolean verdict bands are at or below 0.20 and at or above 0.80; category/level verdicts require a leading-option probability of at least 0.85 after applicable controls. Fixed checks and navigation tools have their own thresholds, described in their references and design.

The footer reports calls · questions · cost · cache · time: request count, questions judged, reported USD cost, cache hits/requests and elapsed time. A tool invocation may require several requests for batching or controls. Missing cost reporting is not evidence of a free request.

In a final report, explicitly identify conclusions marked unsure or abstain as unconfirmed by Jev. If subsequent reading settles them, distinguish that verification from the tool's result and cite the decisive evidence. Otherwise retain the uncertainty in your summary and recommendation.

Usage guidance for pi and omp

The extension supplies the shared reading guide in both hosts. omp discovers enabled npm plugin rules during normal startup; pi does not automatically discover the package's rules/ directory. In pi, the same decision policy is part of the jev_ask tool guidelines, so it is present whenever jev_ask is active. A forced opaque prompt override may bypass this integration; disabled tools or disabled omp rules are not covered. This README block is recommended usage guidance, not itself an installed instruction:

Before concluding that a failure is a code bug, an incorrect test or an environment problem, or that a plan matches documentation, pass the relevant files to jev_ask and weigh its answer against your own reading. Include both the failing test and the code it exercises; identify any conclusion that remains unconfirmed.

MCP clients receive the guide as server instructions, which some clients ignore. Add the agent instructions to the project's CLAUDE.md, AGENTS.md or Kiro steering file.

Data and command safety

Repository evidence, notes and optional command output are sent to your configured endpoint. Review its data-handling policy before using confidential repositories. See security guidance.

File collection is confined to the repository: absolute paths, parent traversal, escaping symlinks, Git metadata and internal URLs are not file inputs. Build output, binaries, lockfiles and oversized files are skipped or refused with visible limits; evidence is not silently truncated into a verdict. This confinement does not sandbox a command. jev_ask commands can read, write or access the network with the host's shell permissions. omp uses execution approval for commands; pi does not supply an additional per-tool command approval; MCP clients apply their own tool approval, and the server marks jev_ask as not read-only. Set JEV_TOOLS_ALLOW_COMMAND=0 to disable them.

Automatic documentation check

On a dirty tree, the extension can check existing Markdown documentation once at run end against changes from HEAD, including untracked files. A flagged existing sentence can request one additional turn to update it or explain why it remains correct. Merely unsure sections do not trigger another turn. Missing configuration, disabled automation, invalid/exhausted session budgets or a clean tree skip the check. Errors and timeout do not block the host. This is not a check for every missing documentation obligation. The MCP server has no run-end hook; there, call jev_check_diff with check: "docs" before finishing.

Known limits

Static evidence and probability do not prove execution, safety or completeness. Import closure cannot discover every relationship; dynamic code, unsupported syntax and optional parser failures leave explicit gaps. No findings is not proof that unseen callers or documentation are correct. Test selection considers existing discovered scenarios, not whether a new scenario must be added. Session caching cannot establish the identity or stability of a moving model alias.

Development and contributions

See CONTRIBUTING.md, CHANGELOG.md, design and architecture decisions. Development checks run locally without contacting a judgment endpoint:

npm ci --include=optional
npm run typecheck
npm run check:imports
npm run lint
npm test

Internal source modules are implementation details, not a stable library interface.

License

MIT.