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TAO-MINGYU

Codex to OpenCode MCP Server

by TAO-MINGYU

Codex to OpenCode MCP Server

Un pequeño servidor local de MCP (Model Context Protocol) que permite a Codex delegar trabajo de programación en OpenCode. Usa el SDK oficial de MCP para Python, el transporte stdio y un subproceso asíncrono de OpenCode.

Herramientas

opencode_execute

opencode_execute(
    task: str,
    working_directory: str,
    model: str | None = None,
    reasoning_effort: str | None = None,
    timeout: int = 1800,
)

Ejecuta este comando sin shell:

opencode run --format json --dir <working_directory> --auto [--model <model>] [--variant <reasoning_effort>] <task>

reasoning_effort se corresponde con la opción --variant específica del proveedor de OpenCode. Los valores comunes incluyen minimal, low, medium, high y max, pero las variantes disponibles las define el proveedor y el modelo seleccionados. El servidor MCP acepta a propósito cualquier valor no vacío, en lugar de imponer una enumeración específica del proveedor.

Ejemplo:

opencode_execute(
    task="Implement uncertainty propagation and run the unit tests.",
    working_directory="C:\\path\\to\\NuSR",
    model="pinche_10/gpt-5.6-sol",
    reasoning_effort="high",
    timeout=1800,
)

Devuelve una salida estructurada que contiene:

  • éxito, timeout, código de salida y tiempo transcurrido;

  • el ID de la sesión de OpenCode y el resumen final del asistente;

  • las llamadas a herramientas de OpenCode completadas y los errores de las llamadas;

  • capturas acotadas de stdout/stderr;

  • un git status --short final, un git diff --stat y un diff unificado acotado.

Los campos de Git son instantáneas posteriores a la ejecución. Pueden incluir cambios que ya existían antes de la llamada. El contenido de texto de los archivos sin seguimiento se representa como parches de archivo nuevo; los archivos binarios sin seguimiento se informan con su ruta y tamaño.

opencode_check

Resuelve el ejecutable de OpenCode configurado y ejecuta opencode --version sin modificar el entorno.

Related MCP server: BoundedRelay

Instalación

Requisitos: Python 3.11+, Git (opcional para informar diffs) y OpenCode.

git clone https://github.com/TAO-MINGYU/codex_to_opencode.git
cd codex_to_opencode
uv venv --python 3.11 .venv
uv pip install --python .venv\Scripts\python.exe -e ".[dev]"

OpenCode debe instalarse y autenticarse de forma independiente. Verifícalo primero:

opencode --version
opencode auth list

La aplicación de escritorio de OpenCode y la CLI de OpenCode son puntos de entrada distintos en Windows. La invocación de OpenCode.exe --version que abre la GUI y no imprime nada no es una CLI utilizable. Instala la CLI oficial cuando sea necesario:

npm install -g opencode-ai

Si opencode no está en PATH, define OPENCODE_MCP_COMMAND con la ruta absoluta del ejecutable. En las instalaciones npm de Windows, prefiere el binario nativo incluido en node_modules\opencode-ai\bin\opencode.exe; el servidor también detecta y omite automáticamente el envoltorio opencode.cmd.

Conectar Codex

Añade el servidor a través de la CLI de Codex, lo que evita tener que editar la configuración manualmente:

codex mcp add opencode --env OPENCODE_MCP_COMMAND=C:\path\to\opencode.exe -- C:\path\to\opencode-mcp\.venv\Scripts\python.exe -m opencode_mcp.server

Cuando OpenCode ya está en PATH, omite la opción --env:

codex mcp add opencode -- C:\path\to\opencode-mcp\.venv\Scripts\python.exe -m opencode_mcp.server

Luego verifica el registro:

codex mcp list

Reinicia Codex después de cambiar la configuración de MCP. El servidor escribe mensajes de protocolo únicamente en stdout y envía los logs a stderr, como requiere para los servidores MCP stdio.

Configuración

Variable de entorno

Valor por defecto

Significado

OPENCODE_MCP_COMMAND

opencode

Nombre del ejecutable o ruta absoluta

OPENCODE_MCP_ARGS

[]

Matriz JSON insertada después del ejecutable (útil para wrappers/pruebas)

OPENCODE_MCP_AUTO_APPROVE

true

Añade el indicador de permisos --auto de OpenCode

OPENCODE_MCP_MAX_OUTPUT_BYTES

2097152

Bytes finales que se conservan de forma independiente para stdout/stderr

OPENCODE_MCP_LOG_LEVEL

INFO

Nivel de log del servidor escrito en stderr

Si se establece la aprobación automática en false, OpenCode rechaza los permisos que no puede solicitar de forma interactiva:

$env:OPENCODE_MCP_AUTO_APPROVE = "false"

Debug

Ejecuta las pruebas automatizadas:

.venv\Scripts\python.exe -m pytest --cov=opencode_mcp --cov-fail-under=80
.venv\Scripts\python.exe -m ruff check .
.venv\Scripts\python.exe -m ruff format --check .

Ejecuta el servidor con MCP Inspector:

uv run --python 3.11 --with-editable ".[dev]" mcp dev src\opencode_mcp\server.py

El timeout de la herramienta MCP debe ser ligeramente superior al timeout pasado a opencode_execute; de lo contrario, Codex puede cancelar la solicitud MCP antes de que el servidor pueda terminar OpenCode y devolver los diagnósticos.

Modelo de seguridad

opencode_execute es una herramienta con capacidad de escritura y, a propósito, potencialmente destructiva. Concede a OpenCode los mismos permisos de sistema de archivos y procesos que tiene el servidor MCP. La implementación:

  • nunca invoca un shell para las tareas de OpenCode;

  • exige una ruta absoluta existente del directorio de trabajo;

  • limita la salida capturada para proteger el contexto de Codex;

  • termina el árbol de procesos de OpenCode en ejecución si se agota el timeout o si la petición MCP se cancela;

  • desactiva la actualización automática de OpenCode durante las ejecuciones delegadas;

  • marca la herramienta MCP como no idempotente y de forma potencialmente destructiva.

Usa una cuenta de sistema operativo con privilegios restringidos o un sandbox cuando delegues tareas o repositorios no confiables.

Available Tools

2 tools
opencode_checkCheck the local OpenCode installationA
Read-onlyIdempotent

Resolve the configured OpenCode executable and report its version.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

Output Schema

ParametersJSON Schema
NameRequiredDescription
errorYes
commandYes
versionYes
availableYes
resolved_executableYes

TDQS

A4.5/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds behavioral detail beyond those annotations by stating the tool resolves a configured executable, which implies reading configuration and locating a binary. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

A single, front-loaded sentence states the key action and outcome, with no filler or redundant detail. Every word earns its space.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool has no parameters, a complete annotation set, and an output schema, so the description only needs to convey the high-level purpose and behavior. It does so completely for this simple check operation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There are zero parameters, so the baseline is 4. The description does not need to explain any parameters, and the schema fully covers them.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb-resource pair: 'Resolve the configured OpenCode executable and report its version.' It clearly identifies both the action and the subject, and the title reinforces the purpose. It is also easily distinguishable from the sibling tool opencode_execute, which implies running commands rather than checking the installation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies a clear context: this is a verification or preflight check of the local OpenCode installation, distinct from execution. While it does not explicitly cite when-or-when-not to use it relative to opencode_execute, the 'check' framing and resolved-executable behavior provide clear usage context without exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

opencode_executeExecute a coding task with OpenCodeA
Destructive

Delegate one repository coding task to OpenCode.

OpenCode runs non-interactively in the supplied directory, may read and modify files, execute terminal commands, run tests, and use Git. The result contains OpenCode's final text, observed tool calls, diagnostics, and the final Git working-tree diff. The Git diff is a post-run snapshot and can include changes that existed before this call.

ParametersJSON Schema
NameRequiredDescriptionDefault
taskYesComplete coding task and acceptance criteria for OpenCode.
modelNoOptional OpenCode model in provider/model form; omit for its configured default.
timeoutNoMaximum execution time in seconds (default 1800).
reasoning_effortNoOptional provider-specific reasoning effort passed to OpenCode as --variant, for example minimal, low, medium, high, or max.
working_directoryYesAbsolute path to the existing project directory OpenCode may modify.

Output Schema

ParametersJSON Schema
NameRequiredDescription
modelYes
errorsYes
stderrYes
stdoutYes
successYes
summaryYes
git_diffYes
exit_codeYes
timed_outYes
git_statusYes
session_idYes
git_diff_statYes
elapsed_secondsYes
output_truncatedYes
reasoning_effortYes
tool_invocationsYes
working_directoryYes
git_diff_truncatedYes

TDQS

A3.8/5.0
Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds meaningful behavior over the annotations (destructiveHint=true, readOnlyHint=false) by disclosing non-interactive execution, possible file modifications, CLI/Git actions, and execution of tests. It also warns that the returned Git diff is a post-run snapshot and may include pre-existing changes. This is useful, though it does not enumerate every destructive action or limitation.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is focused: one purpose-driven opening sentence followed by a terse but information-dense paragraph about behavior and result shape. Every sentence earns its place, including the important Git-diff caveat. The length is appropriate for the tool's complexity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With a complete input schema and an output schema present, the description covers the main operational ambiguity: non-interactive execution, mutation of files, and the non-isolated nature of the Git diff. It is mostly complete, but it leaves the distinction versus opencode_check unstated, and it does not describe interaction between the timeout/model parameters and the result.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the parameter descriptions in the schema already carry the meaning for task, working_directory, model, timeout, and reasoning_effort. The tool description does not add extra parameter syntax, examples, or semantic clarifications beyond what the schema provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description immediately states a specific operation: delegating one repository coding task to OpenCode, and enumerates what the tool can do (read/modify files, run commands, tests, Git). It is clear, but it does not explicitly contrast with the sibling tool opencode_check, so it stops short of full differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The first sentence implies the usage: delegate a coding task to OpenCode. The description also clarifies that it runs non-interactively in a repository, which helps the agent set expectations. However, there is no explicit 'when not to use' or comparison with the sibling opencode_check; usage guidance is present but largely implicit.

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. 2 tool updatesv0.1.0
    • First observedopencode_check
    • First observedopencode_execute

TDQS

A4/5.0

Scored across 2 tools

Disambiguation4/5

The two tools have clearly distinct roles: opencode_execute delegates a coding task, while opencode_check resolves the executable and reports its version. There is no realistic confusion between performing an action and checking the installation.

Naming Consistency5/5

Both tools use the same opencode_ prefix followed by a concise imperative verb, maintaining a consistent snake_case pattern. Though the prefix is a product name, the convention is uniform and predictable.

Tool Count3/5

Two tools is at the low end of typical server scope and feels thin for a coding integration. However, the narrow focus on delegating a single task plus a health check is reasonable enough to be borderline appropriate.

Completeness4/5

The server covers its core purpose: opencode_execute handles task delegation, and opencode_check verifies the underlying executable. Obvious lifecycle tools such as cancellation or querying current task status are absent, but they fall outside the stated minimal purpose.

Maintenance

ActivitySlowing
ResponsivenessNo issues

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