Everything Server - Features

Architecture | Project Structure | Startup Process | Server Features | Extension Points | How It Works

Protocol eras

The server serves two protocol eras from one process, over stdio and over Streamable HTTP. A client's first message picks its era:

• 2026-07-28 (modern): the client opens with server/discover, with no initialize and no session, and sends its protocol version, identity and capabilities in each request's _meta.
• 2025-era (legacy, 2024-10-07 through 2025-11-25): the client opens with the initialize handshake. The HTTP+SSE transport serves this era only.

Each feature below is marked both, 2026-07-28 or 2025-era. Roots, sampling and logging are deprecated as of 2026-07-28 (SEP-2577), as is the HTTP+SSE transport; they stay available and are labelled deprecated in their descriptions.

Feature	2026-07-28	2025-era
Discovery	server/discover	initialize
Client input (elicitation, sampling, roots)	in-band: the tool returns input_required, the client retries	the SDK's legacy shim sends real server-to-client requests for the same handler
State across rounds	requestState, signed and expiring	the same, replayed by the shim
Change notifications	on a subscriptions/listen stream the client opened	unsolicited, or after resources/subscribe
Log level	per request, _meta io.modelcontextprotocol/logLevel (none named: no logs)	per session, logging/setLevel
Tasks	the io.modelcontextprotocol/tasks extension	not served
Cache hints	ttlMs / cacheScope on lists, reads and server/discover	not sent
x-mcp-header	mirrored into Mcp-Param-* headers over Streamable HTTP	not mirrored

Tools

• echo (tools/echo.ts), both: Echoes the provided message: string. Uses Zod to validate inputs.
• get-annotated-message (tools/get-annotated-message.ts), both: Returns a text message annotated with priority and audience based on messageType (error, success, or debug); can optionally include an annotated image.
• get-env (tools/get-env.ts), both: Returns all environment variables from the running process as pretty-printed JSON text. Every name is returned, but the value of a credential-like name (one with a KEY, TOKEN, SECRET, PASSWORD, PASSWD, CREDENTIAL, AUTH or COOKIE segment between underscores, in any case) is replaced with "<redacted>". Set GET_ENV_INCLUDE_SECRETS=1 (or true) in the server's environment to return every value unmasked, for debugging.
• get-header-params (tools/get-header-params.ts), both: Returns its region argument and the Mcp-Param-Region HTTP header it arrived in. Its input and output schemas are plain JSON Schema 2020-12, and region carries x-mcp-header: "Region", so a 2026-07-28 Streamable HTTP client mirrors it into that header and the server refuses a call whose header disagrees with the body (-32020). The header is null on stdio and for a 2025-era client.
• get-resource-links (tools/get-resource-links.ts), both: Returns an intro text block followed by multiple resource_link items. For a requested count (1–10), alternates between dynamic Text resources (even IDs) and Blob resources (odd IDs), using URIs from resources/templates.ts.
• get-resource-reference (tools/get-resource-reference.ts), both: Accepts resourceType (text or blob) and resourceId (positive integer). Returns a concrete resource content block (with its uri, mimeType, and data) with surrounding explanatory text.
• get-roots-list (tools/get-roots-list.ts), both, deprecated: Asks the client for its roots with a multi-round-trip request (inputRequired.listRoots()) and lists them. Needs client capability roots.
• gzip-file-as-resource (tools/gzip-file-as-resource.ts), both: Accepts a name and data (URL or data URI), fetches the data subject to size/time/domain constraints, compresses it, and returns either a resource_link (default) or an inline resource depending on outputType, with mimeType: application/gzip. The linked resource is registered as a session resource at demo://resource/session/<name> for a 2025-era client, and stored for ten minutes at a minted demo://resource/minted/<id>/<name> for a 2026-07-28 client.
• get-structured-content (tools/get-structured-content.ts), both: Demonstrates structured responses. Accepts location input and returns both backward‑compatible content (a text block containing JSON) and structuredContent validated by an outputSchema (temperature, conditions, humidity).
• get-sum (tools/get-sum.ts), both: For two numbers a and b calculates and returns their sum. Uses Zod to validate inputs.
• get-tiny-image (tools/get-tiny-image.ts), both: Returns a tiny PNG MCP logo as an image content item with brief descriptive text before and after.
• simulate-research-query (tools/simulate-research-query.ts), 2026-07-28: Runs as a task on the tasks extension. The call returns a task handle; the task works through four stages, one a second, which the client follows with tasks/get. With ambiguous: true and an elicitation-capable client it pauses at input_required, carrying a clarification request the client answers with tasks/update. Needs a client that declares the extension.
• toggle-simulated-logging (tools/toggle-simulated-logging.ts), 2025-era, deprecated: Starts or stops simulated, random‑leveled logging for the connection. Respects the level the client set with logging/setLevel.
• toggle-subscriber-updates (tools/toggle-subscriber-updates.ts), 2025-era, deprecated: Starts or stops simulated resource update notifications for URIs the connection has subscribed to with resources/subscribe.
• trigger-elicitation-request (tools/trigger-elicitation-request.ts), both: Asks for a form of every field type form-mode elicitation supports (strings, numbers, booleans, enums, and format validation) with a multi-round-trip request, and returns the resulting action/content. Needs client form-mode elicitation: elicitation.form, or an elicitation object that declares neither mode.
• trigger-elicitation-request-async (tools/trigger-elicitation-request-async.ts), 2026-07-28: Runs as a task whose input_required status carries a form elicitation; the client answers with tasks/update and the task completes with a summary. Needs a client that declares the tasks extension and form-mode elicitation.
• trigger-list-changed (tools/trigger-list-changed.ts), both: Sends notifications/<list>/list_changed for tools, prompts or resources: on 2026-07-28 to each subscriptions/listen stream that asked for that list, on a 2025-era connection unsolicited.
• trigger-log-messages (tools/trigger-log-messages.ts), both, deprecated: Sends one log message at each level during the call. A 2026-07-28 request gets those at or above the level its _meta names (none if it names none); a 2025-era client those at or above its logging/setLevel level.
• trigger-long-running-operation (tools/trigger-long-running-operation.ts), both: Simulates a multi-step operation over a given duration and number of steps; reports progress via notifications/progress when a progressToken is provided by the client. Honors cancellation: a cancelled call clears its timer and sends no further progress.
• trigger-multi-step-elicitation (tools/trigger-multi-step-elicitation.ts), both: Asks for a name, then for a favorite color addressed by that name, carrying the first answer to the second round in requestState. The state is HMAC-signed and expires after ten minutes; a tampered or expired one is refused with -32602. A blank name or a color that is not a choice is asked again. Needs form-mode elicitation.
• trigger-resource-update (tools/trigger-resource-update.ts), both: Sends notifications/resources/updated for a URI: on 2026-07-28 to each listen stream whose resourceSubscriptions name it, on a 2025-era connection once the client has subscribed to it.
• trigger-sampling-request (tools/trigger-sampling-request.ts), both, deprecated: Asks the client's LLM for a completion with a multi-round-trip request, using the provided prompt and maxTokens; returns the LLM's response payload. Needs client capability sampling.
• trigger-sampling-request-async (tools/trigger-sampling-request-async.ts), 2026-07-28, deprecated: Runs as a task whose input_required status carries a sampling request; the client answers with tasks/update and the task completes with the result. Needs a client that declares the tasks extension and sampling.
• trigger-url-elicitation (tools/trigger-url-elicitation.ts), both: Directs the user to a URL (URL-mode elicitation). On 2026-07-28 the elicitation comes in-band (input_required), with no elicitationId. On a 2025-era connection it issues an elicitation/create request in URL mode with an elicitationId, or throws MCP error -32042 (UrlElicitationRequiredError) when errorPath=true. On the error path the prerequisite elicitation it returns points at a different URL than the failing request (https://modelcontextprotocol.io); when the client satisfies it and retries the same call, the retry ignores errorPath and proceeds via the request path, so the client does not loop on the same error. The retry marker is one-shot per (url, elicitationId) on the connection: it is cleared on the recognized retry, so re-running the error path with identical arguments without an intervening prerequisite is treated as a retry and proceeds. Needs client capability elicitation.url.

On a 2025-era connection the tools that need a client capability are registered only for a client that declared it at initialize. On 2026-07-28 they are always listed, because the capabilities arrive with each request, and the SDK refuses a call whose embedded request the client did not declare (-32021).

Prompts

• simple-prompt (prompts/simple.ts): No-argument prompt that returns a static user message.
• args-prompt (prompts/args.ts): Two-argument prompt with city (required) and state (optional) used to compose a question.
• completable-prompt (prompts/completions.ts): Demonstrates argument auto-completions with the SDK’s completable helper; department completions drive context-aware name suggestions.
• resource-prompt (prompts/resource.ts): Accepts resourceType ("Text" or "Blob") and resourceId (string convertible to integer) and returns messages that include an embedded dynamic resource of the selected type generated via resources/templates.ts.

Resources

• Dynamic Text: demo://resource/dynamic/text/{index} (content generated on the fly)
• Dynamic Blob: demo://resource/dynamic/blob/{index} (base64 payload generated on the fly)
• Static Documents: demo://resource/static/document/<filename> (serves files from src/everything/docs/ as static file-based resources; a 2026-07-28 read carries a one-hour public cache hint)
• Session Scoped, 2025-era: demo://resource/session/<name> (per-session resources registered dynamically; available only for the lifetime of the session)
• Minted, 2026-07-28: demo://resource/minted/<id>/<name> (resources a tool created, under a server-minted id; readable by any client that has the URI, for ten minutes; the process keeps at most 100 of them and 64 MiB of content, dropping the oldest first)
• Collections: demo://resource/collection/summer-specials, demo://resource/collection/by-category/{category} and demo://resource/collection/item/{itemId} (resources/collections.ts; one resources/read of a collection returns several contents, one per item, each under its item's own URI, which reads back on its own; category and itemId complete)

A read of a resource that does not exist (an unknown URI, a template id that is not a positive integer, a collection category or item that is not in the catalog, an expired minted resource) is answered with -32602 and the URI in the error's data.

Resource Subscriptions and Notifications

• 2026-07-28: a client opens a subscriptions/listen stream whose filter names the notifications it wants (toolsListChanged, promptsListChanged, resourcesListChanged, and resourceSubscriptions for per-resource updates). trigger-list-changed and trigger-resource-update publish onto those streams; over Streamable HTTP, through the handler's subscription bus, so a change made in one request reaches streams other requests opened.
• 2025-era: clients subscribe and unsubscribe to resource URIs with resources/subscribe and resources/unsubscribe. toggle-subscriber-updates starts or stops a per-connection interval that emits notifications/resources/updated { uri } for the URIs that connection subscribed to, and trigger-resource-update sends one on demand. List changes arrive unsolicited.
• Each client's subscriptions belong to the server instance serving its connection, so concurrent clients are independent.

Icons

Both. The server demonstrates icons with light and dark themes (SEP-973). Its serverInfo (in initialize and in server/discover) and every entry of tools/list, prompts/list, resources/list and resources/templates/list carry an icons array of two scalable SVG icons, one with theme: "light" (drawn for a light background) and one with theme: "dark". Each kind has its own glyph: a server rack, a wrench for tools, a speech bubble for prompts, a document for resources, and a document with braces for templates. The icons are inline data: URIs, so a client fetches nothing; they are defined in server/icons.ts.

Logging

Logging is deprecated as of 2026-07-28 (SEP-2577) and remains available on both eras.

• 2026-07-28: a request names its log level in _meta (io.modelcontextprotocol/logLevel); a request that names none gets no log messages. Use trigger-log-messages to see the filter at work.
• 2025-era: clients set the minimum level for the session with logging/setLevel. toggle-simulated-logging starts or stops periodic log messages of varying levels (debug, info, notice, warning, error, critical, alert, emergency).

Tasks

2026-07-28. The server implements the server side of the tasks extension (io.modelcontextprotocol/tasks, SEP-2663), advertised under capabilities.extensions in server/discover. simulate-research-query, trigger-sampling-request-async and trigger-elicitation-request-async answer tools/call with a task handle (resultType: "task") for a client that declares the extension, and serve:

• tasks/get: the task's status, statusMessage, ttlMs and pollIntervalMs, plus its inputRequests while input_required and its result once completed;
• tasks/update: the client's inputResponses to the outstanding input requests;
• tasks/cancel: stop a task that has not finished.

A task tool called by a client whose request does not declare the extension, or the capability its task asks for input with (sampling for trigger-sampling-request-async, form-mode elicitation for trigger-elicitation-request-async), is refused with -32021 (missing required client capability), naming what is missing in data.requiredCapabilities; so is a tasks/* request from a client without the extension. An unknown or expired task, and a tasks/update whose answers exceed 64 KiB serialized (counted in UTF-8 bytes), are refused with -32602. A tasks/cancel is acknowledged whatever the task's status (cancellation is cooperative), and a finished task stays as it ended. An update's answers to requests that are not outstanding (never issued, already answered, or sent while the task is not waiting for input) are ignored, as the extension asks. Each input request a task makes has its own key, never reused once answered, so a request asked again after an answer that does not fit gets a new key (form-2, sampling-2). The process keeps at most 100 tasks, each until its TTL; at that limit a new task is refused with a tool error. The task id is a server-minted UUID, so a task lives across requests (each 2026-07-28 HTTP request is served by a fresh server instance) and is reached only through its handle. A task's progress is computed from the clock when it is read, so nothing runs in the background.

The 2025-11-25 core task methods (tasks/result, tasks/list, task-augmented requests) are not served: SDK v2 removed the experimental layer they were built on.