A thin stdio MCP server that runs a local coding-agent CLI headlessly and exposes it as a single run tool. It ships two flavors, selected by argument:

Argument	Wraps	Headless command
`codex`	OpenAI Codex CLI	`codex exec`
`opencode`	OpenCode CLI	`opencode run`

It is designed to be launched on a user's own machine by the SealGate daemon over a stdio tunnel, so the coding agent runs locally (with the user's own CLI auth and config) while every tool call is mediated by the SealGate data firewall.

Usage

The wrapped CLI (codex or opencode) must already be installed and authenticated on PATH on the machine that runs this server. This package does not install or configure the CLI.

# Wrap the Codex CLI:
npx -y @sealgate/agent-cli-mcp codex

# Wrap the OpenCode CLI:
npx -y @sealgate/agent-cli-mcp opencode

# Pin a default model / reasoning effort at launch (codex shown):
npx -y @sealgate/agent-cli-mcp codex --model gpt-5-codex --effort high

The server speaks MCP over stdio and exposes one tool:

`run`

Run a single headless coding task.

Field	Type	Required	Description
`prompt`	string	yes	The task or question for the coding agent.
`cwd`	string	no	Absolute path to the working directory. When omitted, a fresh temp dir is used.
`model`	string	no	Override the model (passed through to the CLI as-is).
`effort`	enum	no	`minimal`\|`low`\|`medium`\|`high` reasoning effort. Codex only.

model and effort can also be pinned server-wide at launch, so a marketplace entry sets them once instead of every caller passing them: pass --model <m> / --effort <e> after the agent selector, or set AGENT_CLI_MCP_MODEL / AGENT_CLI_MCP_EFFORT. A per-call run argument overrides the server default; a launch flag overrides the env var. effort is ignored for OpenCode.

Progress logs are streamed by the CLI to stderr; the tool returns the CLI's final output. On a non-zero exit or timeout, isError is set and stdout/stderr are included for debugging.

While a run is in flight the server emits MCP notifications/progress (when the caller supplies a progressToken), carrying the latest stderr line so the call does not look hung. Clients that reset their request timeout on progress stay alive through long reasoning; see the timeout note below.

Timeouts

There are two independent clocks, and they are usually confused:

The MCP client's request timeout. The client that calls run decides how long to wait for a response. A headless coding agent can reason for minutes while emitting only stderr, so a client with a short request timeout aborts a perfectly healthy run. This server mitigates that by sending progress heartbeats (above); a client should enable its "reset timeout on progress" behavior (and a generous max total timeout) to benefit. This is the clock that usually fires. Raising AGENT_CLI_MCP_TIMEOUT_MS does not affect it.
This server's subprocess cap (AGENT_CLI_MCP_TIMEOUT_MS). A hard ceiling on how long the wrapped CLI may run before it is killed. It is the backstop for a genuinely stuck CLI, not the knob for "the client timed out".

Environment

Variable	Default	Description
`AGENT_CLI_MCP_TIMEOUT_MS`	`1800000`	Per-run subprocess timeout in milliseconds (hard cap).
`AGENT_CLI_MCP_HEARTBEAT_MS`	`10000`	Interval between progress heartbeats while a run is live.
`AGENT_CLI_MCP_MODEL`	(unset)	Server-wide default model; a launch flag or per-call arg wins.
`AGENT_CLI_MCP_EFFORT`	(unset)	Server-wide default reasoning effort (codex).

Security notes

Arguments are passed as argv with shell: false, so no shell is spawned and the prompt cannot inject shell commands into the launcher.
The coding agent itself can read and modify files in cwd and run commands, subject to its own sandbox/approval configuration. In the marketplace catalog the run tool is classified SECRET (write + private-read + untrusted-read) so the SealGate firewall treats it as maximally sensitive.

Development

npm install
npm run build       # tsc -> dist/
npm run typecheck

Publishing is automated: pushing a tag agent-cli-mcp-v<version> triggers .github/workflows/publish-agent-cli-mcp.yaml, which builds and publishes to npm (requires the NPM_TOKEN repository secret). See that workflow for the first-run setup.