Build MCP Use Server

Build mcp-use Server

Server-side mechanics for mcp-use v2 TypeScript MCP servers (the beta npm dist-tag line). This skill owns the v2 API surface; sister skills own structure, clients, agents, and the raw SDK. v1 (mcp-use/server, npm latest) appears here only as migration material.

When to use this skill

Trigger when the target code or request involves any of these:

• Importing MCPServer from mcp-use (root), or code still importing mcp-use/server that must move to v2.
• Defining tools (definition-first { name, description, inputSchema, outputSchema } + callback), resources, or prompts with zod v4 / Standard Schema.
• Server-side ctx work — ctx.auth, ctx.sendLog, ctx.reportProgress, ctx.sendNotification, ctx.client.capabilities(), ctx.requestState, elicitation re-entry.
• OAuth via mcp-use/oauth/* providers (clerk, auth0, workos, supabase, keycloak, better-auth) or oauthCustomProvider.
• MCP Apps / ChatGPT Apps views — views/<name>/view.tsx, the tool view field, structuredContent props, CSP metadata, mcp-use/react hooks (useToolContext, useCallTool, useViewState).
• Streamable HTTP serving — server.listen, server.fetch, toNodeHandler (mcp-use/node), withMcpUse/createNextHandler (mcp-use/next).
• Running mcp-use dev | build | typecheck | start | deploy, the Inspector, tunneling, or the curl handshake on /mcp.
• Production hardening and deploys: mcp-use Cloud, Vercel, Cloudflare Workers, Google Cloud Run, Supabase, Deno, Bun, Hono, Railway, Docker.
• Migrating from mcp-use v1, raw @modelcontextprotocol/sdk servers, or OpenAI Apps-SDK widgets.

Do not use this skill when:

• The code is app-side MCPClient / browser / react client mounting — route to build-mcp-use-client.
• The work is MCPAgent LLM orchestration over MCP tools — route to build-mcp-use-agent.
• The user wants raw official SDK primitives or strict stdio without mcp-use — route v1 @modelcontextprotocol/sdk work to build-mcp-server-sdk-v1, and split-package v2 @modelcontextprotocol/{core,server,client} work to build-mcp-server-sdk-v2 (mcp-use v2 cannot serve stdio).
• The question is layer placement, import direction, or composition-root structure — route to build-clean-mcp-architecture first (see references/00-clean-architecture-coordination.md), then return here for mechanics.

Version stance

This skill teaches v2 (verified against mcp-use@2.0.0-beta.66; exact pins and drift policy in references/00-version-drift.md). Detect which world the project is in before applying anything:

• from "mcp-use/server" anywhere → v1 project → start at references/28-migration/02-v1-to-v2-overview.md.
• Root MCPServer import, views/, mcp-use/oauth/* → v2 project → apply this skill directly.
• Bare npm install mcp-use installs v1 (latest); v2 needs the beta tag.

Coordinate with neighboring skills

Detect intent

Use references/00-reference-index.md only when the intent table is not specific enough and you need an exact filename.

Core rules

• Import MCPServer and server APIs from mcp-use (root). mcp-use/server does not exist in v2.
• Install the beta tag: mcp-use@beta, @mcp-use/cli@beta, scaffold with create-mcp-use-app@beta. Require Node >= 22.22.2 and ESM; install a StandardSchemaWithJSON library in the project (this skill's examples use zod v4).
• Return raw MCP result envelopes (CallToolResult etc.). The v1 helpers still exported are deprecated — only references/05-responses/07-deprecated-v1-helpers.md teaches them, for migration.
• v2 is stateless per request: no session stores in the shipped beta, no post-response push, no ctx.sample(). Cross-request state goes through the requestState codec or your own store.
• Serve over Streamable HTTP only (/mcp by default). Strict stdio is a raw-SDK requirement — route out.
• For views: views/<name>/view.tsx, tool-level view field, outputSchema required, props via structuredContent, hooks from mcp-use/react.
• Work in the actual package or subdirectory the user named; prefer improving an existing server over replacing it.
• Never claim the server is scaffolded, runnable, or verified in a read-only or plan-only run.
• For version-sensitive claims, read references/00-version-drift.md before editing examples or migration guidance.

Workflow

1. Lock target path and execution mode

Identify the concrete path to inspect and edit. Treat the run as plan-only when the environment is read-only, installs are blocked, or the user asked for analysis. Plan-only output must include exact files, install commands, implementation steps, and validation commands — and must not claim runtime validation.

2. Scan what already exists

Inspect the target for:

• package.json: mcp-use version (1.x = v1, 2.x = v2), zod major, "type": "module", @mcp-use/cli
• imports: mcp-use root vs mcp-use/server (v1 signal), mcp-use/oauth/*, mcp-use/react, mcp-use/next
• server shape: new MCPServer(...), tool definitions, views/ directory, view: fields, oauth config
• runtime signals: .mcp-use/build/, Docker, platform config, custom routes, middleware

For existing servers run scripts/audit-server-readiness.sh (usage: scripts/audit-server-readiness.sh.md). For version drift run scripts/check-mcp-use-version.sh (usage: scripts/check-mcp-use-version.sh.md).

Summarize: target path, v1 vs v2, existing server vs none, tools-only vs views, implementation-capable vs plan-only, chosen entry file.

3. Choose the branch

v1 project: do not extend v1 — migrate first via references/28-migration/02-v1-to-v2-overview.md unless the user explicitly wants v1 maintenance (then say the skill's guidance is v2 and scope the change narrowly).

Existing v2 server: follow the intent row for the requested change, then audit nearby mechanics (tools/schemas, results, config, auth, views, deploy).

No server: scaffold with create-mcp-use-app@beta (scripts/scaffold-mcp-use-server.sh automates it) or hand-build from references/02-setup/04-manual-http-server.md. For an existing app, add a side-car per references/02-setup/05-add-to-existing-app.md; for Next.js follow references/19-nextjs-drop-in/.

Underspecified: infer from the existing project when possible; ask only for user-owned choices that block implementation (the exposed service/data, auth policy, tools-only vs. views, or deploy target).

4. Build or extend

Default sequence:

1. entry file and runtime shape (references/02-setup/, references/09-transports/04-runtime-adapters-node-next-fetch.md)
2. MCPServer config (references/08-server-config/)
3. tools with precise zod v4 schemas (references/04-tools/)
4. resources/prompts only when they improve the interface (references/06-resources/, references/07-prompts/)
5. auth, notifications, elicitation, views, proxy — only when the intent requires them
6. custom health routes, logging, security hardening when shipping beyond local dev (references/24-production/)

5. Validate

Pick the smallest set that proves the changed behavior; report only the rung reached.

• read-only scan: files inspected, nothing executed
• static: mcp-use typecheck / npm run build
• local runtime: mcp-use dev serving /mcp; its CLI-owned listener auto-mounts Inspector at /mcp/inspector unless --no-inspector is set. Direct server.listen(), server.fetch, embedded Next.js handlers, and plain mcp-use start do not auto-mount it.
• Inspector: surface observed and called (references/22-validate/01-inspector-walkthrough.md)
• curl protocol probe: use the native modern wire (no initialize) from references/09-transports/02-streamable-http.md, or the legacy compatibility handshake (initialize, tools/list, tools/call) in references/22-validate/02-curl-handshake.md; legacy POSTs require Accept: application/json, text/event-stream.
• unit: server.fetch(new Request(...)) tests (references/22-validate/04-unit-testing-server-fetch.md)
• live client: mcp-use client, tunnel, or test-by-mcpc-cli session (references/22-validate/03-connect-real-clients.md)
• deployed: health route plus a live MCP call against the public URL

For views, verify the text fallback (content) and, when possible, Inspector CSP mode (references/23-debug/03-view-debugging.md). For deploys, walk references/25-deploy/02-pre-deploy-checklist.md.

Decision rules

• Return concise complete content always; add structuredContent when there is an outputSchema, a typed consumer, or view props — and keep the two semantically equivalent.
• Put private or bulky data in _meta; treat structuredContent as model-visible (references/05-responses/06-meta-and-private-data.md).
• Expected failures return isError envelopes; unexpected failures throw (references/05-responses/05-error-handling.md).
• Guard the exact elicitation mode before returning input_required: check ctx.client.capabilities().elicitation?.form for inputRequired.elicit(...) and .url for inputRequired.elicitUrl(...) (references/12-elicitation/01-overview.md, references/16-client-introspection/02-capabilities.md).
• Need model-side generation? The host generates, the tool validates — sampling is gone (references/13-sampling/01-sampling-removed-in-v2.md).
• Views: view.name must match the one-level views/<name>/view.tsx folder; outputSchema is mandatory; declare domains in view.csp; use useCallTool for View → server and useViewTool for host/model → mounted View, never raw fetch.
• One server definition serves both MCP Apps and ChatGPT hosts — never hand-roll window.openai (references/18-mcp-apps/chatgpt-apps/01-dual-protocol.md).

Guardrails

• In an mcp-use server, do not mix in raw official SDK server primitives (@modelcontextprotocol/sdk v1 or @modelcontextprotocol/{core,server} v2); route a raw-SDK implementation to the matching sibling skill instead.
• Never install bare mcp-use for a v2 project — that is v1; pin the beta tag.
• Never use zod v3, CommonJS, or Node < 22 with v2.
• Never use z.any()/z.unknown() where a concrete schema is possible; .describe() every model-filled field.
• Never teach or write v1 response helpers in new code; raw envelopes only.
• Never put secrets in source, logs, structuredContent, view props, or view state.
• Decide Host validation, Origin validation, and CORS separately: localhost listen() auto-enables Host checks; server.fetch() needs explicit allowedHosts; Origin checks require allowedOrigins; CORS headers require cors (references/08-server-config/03-cors-and-allowed-origins.md, references/08-server-config/04-dns-rebinding-and-host-validation.md).
• Never embed the MCP server as middleware inside another framework's app — use the runtime adapters or side-car patterns.
• Never claim session persistence exists in shipped v2 — see references/10-sessions/01-overview-stateless-truth.md.

Validate honestly

For plan-only runs, mark runtime validation blocked and provide the exact commands to run later.

Output contract

Unless the user asks for another format, report:

1. target path, v1-or-v2 verdict, and scan summary
2. chosen branch and entrypoint decision
3. implementation or exact plan
4. validation rung reached, commands run, and blockers
5. if views changed: text fallback and CSP verification state
6. if deploy/production changed: platform deployment ID, source branch/SHA when available, terminal conclusion, exact dashboard/platform URL, checklist state, and live health/operation evidence
7. key references used, with exact paths for the route actually followed

Reference routing

Start with intent or symptoms; use the inventory only as fallback.

• Symptom index: references/00-symptom-index.md
• Version drift: references/00-version-drift.md
• Clean architecture handoff: references/00-clean-architecture-coordination.md
• Full inventory: references/00-reference-index.md
• Bundled scripts: scripts/check-mcp-use-version.sh.md, scripts/audit-server-readiness.sh.md, scripts/scaffold-mcp-use-server.sh.md
• Concepts: references/01-concepts/01-what-is-mcp-use.md, references/01-concepts/02-server-vs-client-vs-agent.md, references/01-concepts/03-transports-overview.md, references/01-concepts/04-stateless-model-and-request-state.md, references/01-concepts/05-mcp-spec-version-history.md, references/01-concepts/06-mcp-apps-and-views-terminology.md, references/01-concepts/07-this-skill-vs-build-mcp-use-client.md
• Setup: references/02-setup/01-prerequisites.md, references/02-setup/02-scaffold-with-create-mcp-use-app.md, references/02-setup/03-template-flags.md, references/02-setup/04-manual-http-server.md, references/02-setup/05-add-to-existing-app.md, references/02-setup/06-package-scripts.md, references/02-setup/07-tsconfig-and-types.md, references/02-setup/08-env-vars.md
• CLI: references/03-cli/01-overview.md, references/03-cli/02-create-mcp-use-app.md, references/03-cli/03-mcp-use-dev.md, references/03-cli/04-mcp-use-build-and-typecheck.md, references/03-cli/05-mcp-use-start.md, references/03-cli/06-mcp-use-deploy-and-cloud.md, references/03-cli/07-login-and-org.md, references/03-cli/08-client-and-screenshot.md, references/03-cli/09-flag-reference.md, references/03-cli/10-environment-variables.md
• Tools: references/04-tools/01-overview.md, references/04-tools/02-registering-a-tool.md, references/04-tools/03-schemas-standard-schema-and-zod-v4.md, references/04-tools/04-describe-and-annotations.md, references/04-tools/05-the-ctx-object.md, references/04-tools/06-validation-pipeline.md, references/04-tools/07-input-schema-vs-output-schema.md, references/04-tools/08-tool-anti-patterns.md, references/04-tools/canonical-anchor.md
• Results: references/05-responses/01-overview-decision-table.md, references/05-responses/02-text-and-content-blocks.md, references/05-responses/03-structured-content-and-output-schema.md, references/05-responses/04-images-audio-binary-resources.md, references/05-responses/05-error-handling.md, references/05-responses/06-meta-and-private-data.md, references/05-responses/07-deprecated-v1-helpers.md, references/05-responses/canonical-anchor.md
• Resources: references/06-resources/01-overview.md, references/06-resources/02-static-resources.md, references/06-resources/03-resource-templates.md, references/06-resources/04-binary-and-image.md, references/06-resources/05-uri-conventions.md, references/06-resources/06-subscriptions-listen.md, references/06-resources/canonical-anchor.md
• Prompts: references/07-prompts/01-overview.md, references/07-prompts/02-static-prompts.md, references/07-prompts/03-prompt-templates.md, references/07-prompts/04-completable-arguments.md, references/07-prompts/05-prompt-engineering.md
• Server config: references/08-server-config/01-mcp-server-constructor.md, references/08-server-config/02-network-basepath-and-endpoints.md, references/08-server-config/03-cors-and-allowed-origins.md, references/08-server-config/04-dns-rebinding-and-host-validation.md, references/08-server-config/05-middleware.md, references/08-server-config/06-custom-routes.md, references/08-server-config/07-lifecycle-listen-fetch-shutdown.md
• Transports: references/09-transports/01-overview.md, references/09-transports/02-streamable-http.md, references/09-transports/03-stateless-and-request-state.md, references/09-transports/04-runtime-adapters-node-next-fetch.md, references/09-transports/05-no-stdio-and-sse-history.md
• Sessions/state: references/10-sessions/01-overview-stateless-truth.md, references/10-sessions/02-session-storage-roadmap.md, references/10-sessions/03-state-patterns-without-sessions.md, references/10-sessions/04-multi-instance-and-scaling.md
• Auth: references/11-auth/01-overview.md, references/11-auth/02-attaching-a-provider.md, references/11-auth/03-ctx-auth-and-user-context.md, references/11-auth/04-permission-guards.md, references/11-auth/05-custom-provider-oauthcustomprovider.md, references/11-auth/06-debugging-checklist.md, references/11-auth/07-oauth-proxy-removed.md, references/11-auth/providers/01-clerk.md, references/11-auth/providers/02-auth0.md, references/11-auth/providers/03-workos.md, references/11-auth/providers/04-supabase.md, references/11-auth/providers/05-keycloak.md, references/11-auth/providers/06-better-auth.md
• Elicitation: references/12-elicitation/01-overview.md, references/12-elicitation/02-form-mode.md, references/12-elicitation/03-url-mode.md, references/12-elicitation/04-multi-round-and-request-state.md, references/12-elicitation/05-anti-patterns.md
• Sampling: references/13-sampling/01-sampling-removed-in-v2.md
• Notifications: references/14-notifications/01-overview.md, references/14-notifications/02-ctx-sendnotification.md, references/14-notifications/03-progress-reporting.md, references/14-notifications/04-list-changed-events.md, references/14-notifications/05-subscriptions-delivery.md, references/14-notifications/canonical-anchor.md
• Logging: references/15-logging/01-overview.md, references/15-logging/02-ctx-sendlog.md, references/15-logging/03-server-and-request-logging.md
• Client introspection: references/16-client-introspection/01-overview.md, references/16-client-introspection/02-capabilities.md, references/16-client-introspection/03-apps-detection.md, references/16-client-introspection/canonical-anchor.md
• Advanced: references/17-advanced/01-proxy-and-gateway.md, references/17-advanced/02-proxy-auth-and-namespacing.md, references/17-advanced/03-openapi-fromopenapi.md, references/17-advanced/04-mcp-use-vs-official-sdk.md, references/17-advanced/canonical-anchor.md
• MCP Apps: references/18-mcp-apps/01-what-are-mcp-apps.md, references/18-mcp-apps/02-mcp-apps-vs-chatgpt-apps-sdk.md, references/18-mcp-apps/03-vocabulary-views.md, references/18-mcp-apps/04-when-to-use-vs-tools-only.md, references/18-mcp-apps/05-host-capability-detection.md, references/18-mcp-apps/anti-patterns.md, references/18-mcp-apps/canonical-anchor.md
• MCP Apps server surface: references/18-mcp-apps/server-surface/01-tool-view-field.md, references/18-mcp-apps/server-surface/02-register-views-and-folder-conventions.md, references/18-mcp-apps/server-surface/03-viewconfig.md, references/18-mcp-apps/server-surface/04-assets-mcp-url-and-serving.md, references/18-mcp-apps/server-surface/05-csp-metadata.md
• MCP Apps react: references/18-mcp-apps/view-react/01-setup-and-providers.md, references/18-mcp-apps/view-react/02-usetoolcontext.md, references/18-mcp-apps/view-react/03-usecalltool.md, references/18-mcp-apps/view-react/04-useviewstate-and-model-context.md, references/18-mcp-apps/view-react/05-display-modes.md, references/18-mcp-apps/view-react/06-followups-and-open-external.md, references/18-mcp-apps/view-react/07-host-context-files-and-size.md, references/18-mcp-apps/view-react/08-theme-and-components.md, references/18-mcp-apps/view-react/09-useviewtool.md
• ChatGPT apps: references/18-mcp-apps/chatgpt-apps/01-dual-protocol.md, references/18-mcp-apps/chatgpt-apps/02-legacy-window-openai-and-skybridge.md, references/18-mcp-apps/chatgpt-apps/03-csp-differences.md, references/18-mcp-apps/chatgpt-apps/04-runtime-detection.md
• Next.js: references/19-nextjs-drop-in/01-overview-withmcpuse.md, references/19-nextjs-drop-in/02-route-and-file-placement.md, references/19-nextjs-drop-in/03-views-in-nextjs.md, references/19-nextjs-drop-in/04-deploying-on-vercel.md
• Inspector: references/20-inspector/01-overview.md, references/20-inspector/02-cli.md, references/20-inspector/03-connection-settings.md, references/20-inspector/04-url-parameters.md, references/20-inspector/05-keyboard-shortcuts-and-palette.md, references/20-inspector/06-integration-and-add-to-client.md, references/20-inspector/07-self-hosting.md, references/20-inspector/08-debugging-chatgpt-apps.md, references/20-inspector/09-changelog-pointer.md
• Tunneling: references/21-tunneling/01-overview.md, references/21-tunneling/02-when-to-tunnel-and-debugging.md
• Validate: references/22-validate/01-inspector-walkthrough.md, references/22-validate/02-curl-handshake.md, references/22-validate/03-connect-real-clients.md, references/22-validate/04-unit-testing-server-fetch.md
• Debug: references/23-debug/01-debugging-workflow.md, references/23-debug/02-transport-debugging.md, references/23-debug/03-view-debugging.md
• Production: references/24-production/01-env-config.md, references/24-production/02-error-strategy.md, references/24-production/03-health-and-custom-routes.md, references/24-production/04-security-hardening.md, references/24-production/05-scaling-stateless.md
• Deploy: references/25-deploy/01-decision-matrix.md, references/25-deploy/02-pre-deploy-checklist.md, references/25-deploy/03-docker.md, references/25-deploy/04-cli-and-org-management.md, references/25-deploy/platforms/01-mcp-use-cloud.md, references/25-deploy/platforms/02-vercel.md, references/25-deploy/platforms/03-cloudflare-workers.md, references/25-deploy/platforms/04-google-cloud-run.md, references/25-deploy/platforms/05-supabase.md, references/25-deploy/platforms/06-deno.md, references/25-deploy/platforms/07-bun.md, references/25-deploy/platforms/08-hono.md, references/25-deploy/platforms/09-railway.md, references/25-deploy/platforms/10-runtime-patterns.md
• Anti-patterns: references/26-anti-patterns/01-sdk-misuse.md, references/26-anti-patterns/02-tool-design.md, references/26-anti-patterns/03-schemas.md, references/26-anti-patterns/04-results.md, references/26-anti-patterns/05-security-and-cors.md
• Troubleshooting: references/27-troubleshooting/01-error-catalog.md, references/27-troubleshooting/02-quick-diagnostic-table.md, references/27-troubleshooting/03-oauth-issues.md, references/27-troubleshooting/04-view-rendering-issues.md, references/27-troubleshooting/05-csp-violations.md, references/27-troubleshooting/06-decision-tree.md
• Migration: references/28-migration/01-from-modelcontextprotocol-sdk.md, references/28-migration/02-v1-to-v2-overview.md, references/28-migration/03-v1-to-v2-imports-server-and-tools.md, references/28-migration/04-v1-to-v2-responses-and-helpers.md, references/28-migration/05-v1-to-v2-auth.md, references/28-migration/06-v1-to-v2-widgets-to-views.md, references/28-migration/07-v1-to-v2-sessions-transports-stdio-sse.md, references/28-migration/08-appssdk-to-mcp-apps.md
• Templates: references/29-templates/01-overview-and-decision-matrix.md, references/29-templates/02-template-mcp-server.md, references/29-templates/03-template-mcp-apps.md, references/29-templates/04-template-blank-and-manual.md
• Workflows: references/30-workflows/01-greenfield-tool-server-to-vercel.md, references/30-workflows/02-views-app-chart-widget.md, references/30-workflows/03-oauth-protected-server-clerk.md, references/30-workflows/04-supabase-oauth-and-deploy.md, references/30-workflows/05-nextjs-drop-in.md, references/30-workflows/06-openapi-to-mcp.md, references/30-workflows/07-proxy-gateway.md, references/30-workflows/08-elicitation-input-required-flow.md
• Canonical examples: references/31-canonical-examples/00-how-to-use-this-cluster.md, references/31-canonical-examples/01-chart-builder.md, references/31-canonical-examples/02-diagram-builder.md, references/31-canonical-examples/03-example-inventory.md