openrouter-subagents

An MCP server and CLI that exposes a model-agnostic "subagent" tool backed by OpenRouter — one API key, every model. It defaults to OpenRouter Fusion (openrouter/fusion), which runs a panel of models in parallel and has a judge model synthesize them into a single answer. Sibling to gpt-subagents-api (OpenAI API key) and gpt-subagents-subscription (ChatGPT subscription), and it ships the same orchestration patterns system.

Note: Uses an OpenRouter API key (Authorization: Bearer …) against the OpenAI-compatible Chat Completions endpoint. Not affiliated with or endorsed by OpenRouter.

Tools

Fusion cost: a Fusion call bills for every panel model plus the judge. Reach for it when multiple perspectives are worth the spend (research, critique, high cost-of-being-wrong); for quick tactical prompts pass a single model id instead.

Reasoning & sampling controls

Any model's reasoning level can be set — the server exposes OpenRouter's full unified reasoning object, and OpenRouter translates it into whatever the target model natively speaks (OpenAI/Grok effort levels, Anthropic thinking budgets, Gemini thinkingLevel, Qwen thinking budgets, on/off flags for models like DeepSeek/GLM). A level a model doesn't support is mapped to the nearest one it offers.

Note for agents (MCP or CLI): if a call fails or any error occurs — timeout, rate limit, model rejection, provider outage — retry the exact same call first (waiting briefly for transient errors). If it keeps failing, report the error and ask; do not downgrade or change the configuration the user set (model, reasoning level/budget, temperature, Fusion panel/judge) without their direct say-so. This rule is also baked into the server's MCP instructions and the CLI --help.

Related MCP server: agentloop

CLI

Everything the MCP server does is also available as a plain shell command — same client, same patterns library, but the answer comes back as raw text on stdout with zero JSON-RPC framing. For agents that can run shell commands, this is the token-cheap way to delegate: no MCP envelope in either direction, and piped stdin means large inputs (diffs, logs, files) never have to be echoed through the model's context at all.

npm run build        # compiles dist/cli.js
npm link             # optional: puts `openrouter-subagents` on your PATH

# ask (the subcommand is optional); raw answer on stdout
openrouter-subagents "why is the sky blue?"
openrouter-subagents ask -m anthropic/claude-haiku-4.5 -e xhigh "prove sqrt(2) is irrational"

# piped stdin becomes the prompt — or the context when a prompt is given
git diff | openrouter-subagents ask -p "review this diff for bugs" -e high
openrouter-subagents ask -p "summarize" --context-file big-report.md -m openai/gpt-5-mini

# patterns
openrouter-subagents patterns
openrouter-subagents pattern two-layer-cross-model-expert

Flags mirror the MCP tool: -m/--model, -i/--instructions (defaults to a terse general-purpose prompt), -p/--prompt, -c/--context (each with a --*-file variant), -e/--effort (none…max), --reasoning-tokens <n>, --reasoning on|off, --hide-reasoning, -t/--temperature, and Fusion's --analysis-models / --judge. --help shows the full reference. Exit codes: 0 success, 2 usage error, 1 API/network error.

Orchestration patterns

Patterns are reusable playbooks (Markdown in patterns/) that describe how to drive the expert tool — splitting work, bundling context, calling the expert, verifying its output against ground truth, and aggregating. They're exposed via list_patterns (catalog) and get_pattern("<name>") (full text), read from disk at call time (no rebuild to add one), and the server's instructions nudge the agent to consult them before non-trivial expert work.

Both patterns ship a rendered diagram under patterns/html/. See patterns/README.md to add your own.

Setup

Requires Node 18+ (uses the global fetch) and an OpenRouter API key.

npm install
npm run build
cp .env.example .env       # then put your key in .env

Get a key at https://openrouter.ai/keys and set OPENROUTER_API_KEY in .env. .env is gitignored and must never be committed — only .env.example is tracked.

Configuring a default Fusion panel + judge (optional)

By default, openrouter/fusion uses OpenRouter's built-in "Quality" preset. You can override that default for every Fusion call from your .env:

# 1–8 panel models that answer in parallel:
OPENROUTER_FUSION_ANALYSIS_MODELS=anthropic/claude-opus-latest,openai/gpt-latest,google/gemini-pro-latest
# the judge that synthesizes them:
OPENROUTER_FUSION_JUDGE_MODEL=anthropic/claude-opus-latest

Precedence is per-call arg > .env default > OpenRouter preset, resolved independently for the panel and the judge: a per-call analysis_models / judge_model on ask_openrouter overrides the matching .env default, and these defaults apply only to openrouter/fusion (they're ignored for any other model).

Register with Claude Code

claude mcp add -s user openrouter-subagents -- node /absolute/path/to/openrouter-subagents/dist/server.js

(Claude Code reads MCP registrations at startup, so a newly added server appears after a full restart.)

How it works

1. ask_openrouter builds an OpenAI-style Chat Completions request (system + user messages).

2. For openrouter/fusion, the panel (analysis_models) and judge (judge_model) are resolved with precedence per-call arg > .env default > OpenRouter's preset, then sent as a plugins: [{ id: "fusion", … }] entry. With none of them set, OpenRouter's built-in Quality preset is used.

3. The request is POSTed to https://openrouter.ai/api/v1/chat/completions with Authorization: Bearer $OPENROUTER_API_KEY; the answer is choices[0].message.content.

4. Fusion is slow (parallel panel + synthesis), so the client uses a generous request timeout (~280s).

Security

• The API key lives in .env (gitignored everywhere); only .env.example (a placeholder) is tracked.

• Outbound instructions / prompt / context are run through a best-effort secret redactor (API keys, tokens, private keys) before they leave your machine — not a guarantee; don't paste highly sensitive data.

• Data boundary: with the default openrouter/fusion, a single call fans your input out to several third-party providers at once (e.g. Anthropic, OpenAI, Google) via OpenRouter.

• Local agent/editor state (.mempalace/, .claude/, CLAUDE.local.md, IDE folders) is gitignored.

License

MIT