mirror of
https://github.com/coder/coder.git
synced 2026-06-02 20:48:20 +00:00
Kyle Carberry
0f86c4237e
Coder's chat (chatd) can now discover and use MCP servers configured in a workspace's `.mcp.json` file. This brings project-specific tooling (GitHub, databases, docs servers, etc.) into the chat without any manual configuration. ## How it works The workspace agent reads `.mcp.json` from the workspace directory (same format Claude Code uses), connects to the declared MCP servers — spawning child processes for stdio servers and connecting over the network for HTTP/SSE — and caches their tool lists. Two new agent HTTP endpoints expose this: - `GET /api/v0/mcp/tools` returns the cached tool list (supports `?refresh=true`) - `POST /api/v0/mcp/call-tool` proxies calls to the correct server On each chat turn, chatd calls `ListMCPTools` through the existing `AgentConn` tailnet connection, wraps each tool as a `fantasy.AgentTool`, and adds them to the LLM's tool set alongside built-in and admin-configured MCP tools. Tool names are prefixed with the server name (`github__create_issue`) to avoid collisions. Failed server connections are logged and skipped — they never block the agent or break the chat. Child stdio processes are terminated on agent shutdown.
89 lines
2.2 KiB
Go
89 lines
2.2 KiB
Go
package agentmcp
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import (
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"errors"
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"net/http"
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"github.com/go-chi/chi/v5"
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"cdr.dev/slog/v3"
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"github.com/coder/coder/v2/coderd/httpapi"
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"github.com/coder/coder/v2/codersdk"
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"github.com/coder/coder/v2/codersdk/workspacesdk"
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)
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// API exposes MCP tool discovery and call proxying through the
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// agent.
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type API struct {
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logger slog.Logger
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manager *Manager
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}
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// NewAPI creates a new MCP API handler backed by the given
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// manager.
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func NewAPI(logger slog.Logger, manager *Manager) *API {
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return &API{
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logger: logger,
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manager: manager,
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}
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}
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// Routes returns the HTTP handler for MCP-related routes.
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func (api *API) Routes() http.Handler {
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r := chi.NewRouter()
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r.Get("/tools", api.handleListTools)
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r.Post("/call-tool", api.handleCallTool)
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return r
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}
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// handleListTools returns the cached MCP tool definitions,
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// optionally refreshing them first if ?refresh=true is set.
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func (api *API) handleListTools(rw http.ResponseWriter, r *http.Request) {
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ctx := r.Context()
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// Allow callers to force a tool re-scan before listing.
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if r.URL.Query().Get("refresh") == "true" {
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if err := api.manager.RefreshTools(ctx); err != nil {
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api.logger.Warn(ctx, "failed to refresh MCP tools", slog.Error(err))
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}
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}
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tools := api.manager.Tools()
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// Ensure non-nil so JSON serialization returns [] not null.
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if tools == nil {
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tools = []workspacesdk.MCPToolInfo{}
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}
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httpapi.Write(ctx, rw, http.StatusOK, workspacesdk.ListMCPToolsResponse{
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Tools: tools,
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})
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}
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// handleCallTool proxies a tool invocation to the appropriate
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// MCP server based on the tool name prefix.
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func (api *API) handleCallTool(rw http.ResponseWriter, r *http.Request) {
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ctx := r.Context()
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var req workspacesdk.CallMCPToolRequest
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if !httpapi.Read(ctx, rw, r, &req) {
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return
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}
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resp, err := api.manager.CallTool(ctx, req)
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if err != nil {
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status := http.StatusBadGateway
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if errors.Is(err, ErrInvalidToolName) {
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status = http.StatusBadRequest
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} else if errors.Is(err, ErrUnknownServer) {
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status = http.StatusNotFound
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}
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httpapi.Write(ctx, rw, status, codersdk.Response{
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Message: "MCP tool call failed.",
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Detail: err.Error(),
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})
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return
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}
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httpapi.Write(ctx, rw, http.StatusOK, resp)
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}
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