Concord MCP

Concord MCP

Let Claude Code, Codex, Cursor, Gemini CLI, and Grok Build talk to each other.

The open-source, local-first communication and coordination layer for AI coding agents. Send live messages across harnesses, detect overlapping work before agents edit, share decisions, and hand off tasks with evidence - through one MCP server.

Demo · Quick start · Supported agents · Website · Contributing

See it work

Two agents in different harnesses can discover each other, exchange messages,and divide work without a human relaying context between them:

Claude Code → Concord   Claim src/app/page.tsx
Codex       → Concord   Claim src/app/page.tsx
Concord     → Codex     Overlap: Claude Code already owns this file
Codex       → Claude    I'll take src/app/api instead. Does that work?
Claude      → Codex     Yes. I'll keep the page and use your API contract.

Run the real Claude Code ↔ Codex demo to watch bothagents resolve an overlapping claim through a live prompt/reply, build a playableapp, transfer ownership, and hand the result to an independent reviewer.

Quick start

npm install -g @concord-ai/concord-mcp
cd /path/to/your/repository
concord setup

Restart your agent clients, then ask two of them to work in the same repository.Concord gives them a shared workspace and makes reachable sessions available fordirect prompts and replies.

concord setup creates the local .concord/ workspace, registers the MCP serverfor Claude, Cursor, Gemini, Grok, and Codex (.mcp.json, .cursor/mcp.json,.gemini/settings.json, .grok/config.toml, and ~/.codex/config.toml) and writesConcord's tool instructions into your client configs (CLAUDE.md, AGENTS.md,.codex/, .cursor/rules/). It merges into existing config rather than replacingit and is safe to re-run.

Setup also detects supported clients and attempts to install their global Concordadapters independently. Use --no-adapters to skip that step or--require-adapters in managed installs that should fail on degraded support.Pass --no-mcp to write only the workspace and instructions while managing MCPregistration yourself.

Supported agents

There is no universal /concord slash command — commands are client-specific.Concord works through MCP tools plus the installed instructions on anyMCP-capable client.

Live delivery depends on the receiving harness and session state. Runconcord adapters status to see which installed agents are reachable and howmessages will be delivered.

Communication is the starting point

Messaging gets agents talking. Concord's shared work-state keeps the resultingcollaboration reliable after the message is delivered.

Concord is not another autonomous agent or orchestrator. It is the shared layeraround your agents: presence, messaging, task memory, ownership, handoffs, andreview state through one small MCP server.

The tools

Writes accept an agent_id, which keeps presence live just by working.inspect_work shows who is here and flags stale claims — an activeclaim whose owning agent has gone away without handing off.

For live agent-to-agent communication, run concord setup, then restart existingclient sessions once. A prompt uses update_work with operation: "prompt", thetarget to_agent_id, content, and an idempotency_key; a reply usesoperation: "reply" and reply_to_message_id. A receipt-bearing adapter steersa busy turn or starts an idle turn. Hook-only integrations leave a durable pullmessage and state that limitation in the result. Delivery fails immediatelywhen the named agent has no reachable endpoint; Concord does not silentlyreroute it.

concord adapters status reports each harness separately, including itsmonitor/controller kind, verified reachability, required action, and versionprobe result. concord adapters install, doctor, and uninstall provide thesame global lifecycle outside repository setup.

Concord resolves the repository workspace automatically. Operations return itsworkspace_id and repository root so a client can detect a misrouted call; theid can be passed explicitly when one server is coordinating multiple roots.

Lifecycle-changing operations use the task's monotonic version asexpected_version. If two agents act on the same version, only the firsttransition succeeds. Assignment leaves work in assigned until the named agentuses transfer_work with action: "accept"; a handoff offer likewise keepsownership with the sender until the recipient accepts. Every ownership changeis retained in an append-only audit history.

What you get

SQLite is the local source of truth, kept in the .concord/ at the root ofthe repo the work is happening in. The MCP server resolves that root fromCONCORD_REPO_ROOT if set, then Claude Code's CLAUDE_PROJECT_DIR (which ClaudeCode sets automatically, even for a user-scoped server), then its workingdirectory — so every agent in one repo shares one store. Set CONCORD_REPO_ROOTwhen running the server somewhere its working directory is not inside the repo.

Linked Git worktrees follow Git's commondir metadata to the primary checkout,so the main checkout and all linked worktrees intentionally share one Concorddatabase and workspace id.

To restrict explicit workspace selection, set CONCORD_ALLOWED_ROOTS to apath-delimited list of allowed repository roots. Without an allowlist, decodedroots must still exist and be directories.

concord setup adds .concord/ to therepository's .gitignore, so the generated workspace stays local by default.Teams that want selected artifacts in PRs can remove that rule or force-add thehuman-readable files:

.concord/
├── concord.db          local source of truth
├── HANDOFF.md          human-readable handoff
├── REVIEW_PACKET.md    review-ready evidence
└── WORK_STATE.json     generated export (optional)

CLI

Concord supports both typed MCP tools and a regular CLI. MCP-capable agents cancall the tools directly; humans and CLI-oriented agents can work with the sameshared workspace through concord commands.

concord setup                # set up local state, instructions, and MCP clients
concord status               # roster, active work, overlaps, stale claims, review-ready
concord dashboard            # live, keyboard-driven view of agents, tasks, alerts, and activity
concord who                  # which agents are present and what they are working on
concord tasks                # list all tracked tasks
concord handoff <task-id>    # print the latest handoff
concord review-packet <id>   # print the latest review packet
concord export markdown      # regenerate .concord/ artifacts
concord doctor               # workspace checks + per-task tool adoption
concord adapters status      # global harness delivery capability matrix

concord --repo ../project status        # select by repository path from anywhere
concord --workspace ws_... status       # select an id returned by a Concord operation

--repo and --workspace are global, mutually exclusive options. The CLI usesthe same CONCORD_REPO_ROOT → CLAUDE_PROJECT_DIR → working-directory priorityand the same linked-worktree canonicalization as MCP.

concord dashboard is a read-only, full-screen local TUI. It refreshes from theshared SQLite workspace every second while keeping agents, tasks, alerts,context, and timeline inside a fixed terminal viewport. Use Tab to changepanes, j/k or the arrow keys to select work, / to filter, ? for help,and q to quit.

Upgrade

npm install -g @concord-ai/concord-mcp@latest
concord --version

Concord checks daily and surfaces available updates in the CLI, MCP tools, anddashboard; concord setup can install one with confirmation, andCONCORD_NO_UPDATE_CHECK=1 disables checks.

What this is / is not

Shared work-state and task memory for coding agents using the same localcheckout. Not an orchestrator, code reviewer, hosted sync service, memoryvector DB, or autonomous coding agent.

See also: Why not just use markdown?

Contributing

See CONTRIBUTING.md and CLAUDE.md. Thisrepo is strictly typed (no any, no typecasts) and modular. Good first issuesare labelled good first issue.

Star History

Privacy & telemetry

Concord sends anonymous product-usage metadata to getconcord.ai so we canmeasure active installations, feature adoption, errors, and performance. Eventscontain random installation/session identifiers, an irreversible per-installworkspace pseudonym, Concord/Node/platform versions, normalized MCP clientmetadata, and MCP tool or CLI command names, outcomes, and durations.

Concord never sends code, raw file or repository paths, remotes, usernames,task or agent identifiers, command arguments, tool inputs/outputs, or taskcontent. Set CONCORD_TELEMETRY_DISABLED=1 (or DO_NOT_TRACK=1) to disabletelemetry. Delivery is best effort and can never make a Concord operation fail.

License

MIT