php-sdk/CHANGELOG.md

Changelog

All notable changes to mcp/sdk will be documented in this file.

0.8.0

• Answer a request over a response stream under the 2026-07-28 lifecycle: StatelessProtocol runs handlers in a fiber, so $gateway->progress() and $gateway->log() work there as they do in the handshake era. The stream opens only if the handler actually emits something and the client's Accept admits text/event-stream, and the choice is made after the handler's first suspension, so a request that turns out to need -32021 or -32602 is still answered with the status the spec fixes for it.
• Honour io.modelcontextprotocol/logLevel (SEP-2575), which replaced the logging/setLevel RPC: a request naming no level receives no notifications/message at all, one naming a level receives the messages at or above it. Adds LoggingLevel::severity() and LoggingLevel::isAtLeast().
• [BC Break] Answer a not-found subject with -32602 (Invalid params) instead of -32002, which the 2026-07-28 revision reserves and forbids emitting (SEP-2164). resources/read picks the code from the revision serving the request — -32602 with the uri in error.data from 2026-07-28 on, -32002 below. prompts/get for an unknown prompt, completion/complete for an unknown reference and tools/call for an unknown tool switch to -32602 in every revision: -32002 was never the code for those. Adds ProtocolVersion::usesInvalidParamsForResourceNotFound().
• Add the multi round-trip requests pattern for the 2026-07-28 lifecycle (SEP-2322): a tools/call or prompts/get handler returning Mcp\Schema\Result\InputRequiredResult comes back as resultType: "input_required" carrying the inputRequests it needs answered and an opaque requestState; the client retries the same request with inputResponses, which the handler reads through RequestContext::getInputContext(). Mcp\Server\Stateless\RequestStateCodec signs and time-bounds the state — set the key with Builder::setRequestStateKey().
• Validate the standard MCP request headers under the 2026-07-28 lifecycle (SEP-2243): Mcp\Server\Stateless\StandardHeaderValidator, set with Builder::setHeaderValidator(), checks that Mcp-Method and Mcp-Name agree with the body they travel with and that a Mcp-Param-* mirrors the argument its tool marked x-mcp-header, answering -32020 when they disagree. Intermediaries route on these headers, so a value contradicting the body has to be refused rather than ignored.
• [BC Break] Mcp\Schema\JsonRpc\Error accepts null as its $id, and getId() may return it. An error response whose id could not be read now omits the member instead of sending "id": "" — which claimed the peer had issued a request with an empty-string id. All the for*() factories default to null, fromArray() accepts a missing or explicitly-null id, and MessageFactory decodes both as an id-less error rather than rejecting them.
• Preserve the original request id on an invalid-but-parseable message (-32600) instead of answering it id-less: InvalidInputMessageException now carries the recoverable id via getRequestId()/setRequestId(), threaded from MessageFactory through to the error response.
• [BC Break] Add the extensions framework SEP-2133 defines, which MCP Apps sits on. ExtensionInterface::getId() now returns the new Mcp\Schema\Extension\ExtensionIdentifier value object instead of a string, which validates the identifier against the _meta key naming rules at construction time. ExtensionInterface also gains getMessages()/getRequestHandlers(), so an extension can contribute the message classes its methods decode into — without which its methods cannot be decoded at all — and the handlers serving them; extensions that only announce a capability can extend the new Mcp\Schema\Extension\AbstractExtension and skip both. MessageFactory::make() takes an $additional list of message classes, and RequestHandlerInterface's result template is now covariant.
• [BC Break] Drop the SDK-only name pattern on ResourceDefinition/ResourceTemplate $name — the spec allows any string (its own examples use main.rs and Project Files). URI/URI-template validation is unchanged.
• Add ClientGateway::supportsExtension(), Client\Builder::enableExtension(), and ClientCapabilities::withExtensions() so clients can negotiate and check protocol extensions (e.g. MCP Apps) the same way servers already do. [BC Break] ServerExtensionInterface is replaced by the side-agnostic Mcp\Schema\Extension\ExtensionInterface.
• Deprecate Roots, Sampling and Logging per SEP-2577 (protocol revision 2026-07-28, earliest removal 2027-07-28). They keep working but using them now triggers a deprecation notice — migrate to tool arguments/resource URIs, a direct LLM provider API, and stderr/OpenTelemetry respectively.
• [BC Break] Gate structuredContent on the negotiated protocol revision: a tool result that's a PHP list (or an object serializing to a JSON array) is now only sent as structuredContent on protocol revisions 2026-07-28+; older revisions omit it and keep the JSON-encoded value in content.
• Add protocol revision negotiation during initialize: the server counter-offers a revision it supports, and the client now fails the handshake instead of continuing on an unagreed revision. Adds Client::getProtocolVersion() and the 2026-07-28 revision.
• Add sampling-with-tools support: sampling requests can include tools and tool-choice preferences, messages support tool-use/tool-result content blocks, and clients advertise sampling.context/sampling.tools via ClientGateway::supportsSamplingTools()/supportsSamplingContext(). A request that violates the spec's tool-flow rules is now rejected with a proper JSON-RPC error instead of being left unanswered.
• [BC Break] SamplingMessage::$content and CreateSamplingMessageResult::$content may now be a list of content blocks instead of just one — use the new getContentBlocks() to always get a list.
• [BC Break] CreateSamplingMessageResult now rejects any role other than assistant, and rejects empty content, per spec.
• Close the remaining schema gaps for 2025-06-18/2025-11-25 and add the 2026-07-28 surface (SEP-2106): url-mode elicitation (ClientGateway::elicitUrl()/supportsElicitationUrl()), Implementation::title, and outputSchema/structuredContent accepting any JSON value rather than only objects.
• Add Mcp\Schema\Content\ResourceLink — reference a resource by URI/name in tool results and prompt messages without embedding its contents.
• Add client-side Roots support: RootsCallbackInterface, Client::sendRootsListChanged(), and server-side ClientGateway::listRoots()/supportsRoots().
• Add ClientGateway::supportsSampling() to check the client's advertised capabilities before sending a sampling request, matching supportsRoots()/supportsElicitation().
• Fix empty tool/resource schemas serializing as [] instead of {} in inputSchema/outputSchema.
• Fix PromptResultFormatter dropping annotations, _meta, and mimeType when a prompt generator returns content as a plain array.
• Add annotations support to ImageContent, matching TextContent/AudioContent.

0.7.0

• Add client-side elicitation support: ElicitationCallbackInterface, ElicitationRequestHandler, and ElicitationException let clients respond to server elicitation requests.
• Defer element loading to the first registry read: loaders now run at request time (first has*/get* call) instead of eagerly at Builder::build(), fixing empty registries under persistent runtimes (e.g. FrankenPHP worker mode) where a loader's data source is not ready at build time. Adds Builder::setLazyLoading() (default on), a public Registry::load(), and an optional LoaderInterface constructor argument on Registry.
• [BC Break] Element loading is lazy by default: loader failures now surface on the first request rather than at Builder::build(), and initialize advertises capabilities from the configured sources rather than the loaded registry. Call Builder::setLazyLoading(false) to restore eager build-time loading.
• Allow [$instance, 'methodName'] as an element handler in Builder::addTool(), addResource(), addResourceTemplate(), and addPrompt(). Unblocks handlers with constructor dependencies that the container-less new $className() fallback cannot build.
• Always emit an items schema for array tool parameters: untyped arrays get items: {} and nullable typed arrays (e.g. string[]|null) keep their element type. Fixes strict clients rejecting tools with "array type must have items" (#151).
• Harden JSON-RPC input parsing: single-message vs batch is now decided from the decoded JSON type (object → single, list array → batch) instead of the raw first byte. Scalars, empty payloads, and non-object batch elements are surfaced as InvalidInputMessageException entries instead of triggering warnings or a TypeError.
• Add maxBatchSize (default 100) to MessageFactory — oversized JSON-RPC batches are rejected before any message is constructed, guarding against amplification.
• Add maxBodyBytes (default 4 MiB) to StreamableHttpTransport — POST bodies exceeding the cap are rejected with 413. Unknown-size/chunked bodies are read incrementally and stopped at the cap so they cannot exhaust memory.
• Reject malformed Mcp-Session-Id headers with a 400 response: a repeated header or a value that is not a valid UUID is now rejected up front instead of surfacing as an uncaught Uuid::fromString() error.
• Extract RFC 9728 metadata serving into ProtectedResourceMetadataHandler, a transport-neutral PSR-15 RequestHandlerInterface that can be mounted directly as a Symfony/Laravel controller; ProtectedResourceMetadataMiddleware now delegates to it (no BC break).

0.6.0

• Add Builder::add(Tool|ResourceDefinition|ResourceTemplate|Prompt $definition, ElementHandlerInterface $handler) for explicit registration of elements whose schema is only known at runtime.
• Add handler interfaces ToolHandlerInterface, ResourceHandlerInterface, ResourceTemplateHandlerInterface, PromptHandlerInterface, and the ElementHandlerInterface marker.
• [BC Break] Renamed Mcp\Schema\Resource to Mcp\Schema\ResourceDefinition. No alias.
• [BC Break] Renamed Mcp\Capability\Registry\Loader\ArrayLoader to Mcp\Capability\Registry\Loader\ReflectedElementLoader.
• [BC Break] Bump default protocol version to 2025-11-25
• Add support for MCP Apps extension in schema and server
• Add extensions to ServerCapabilities and ClientCapabilities and Builder::enableExtension()
• Allow overriding the default name pattern for Discovery
• Add configurable session garbage collection (gcProbability/gcDivisor)
• Add optional title field to ResourceDefinition and ResourceTemplate for MCP spec compliance
• Add ChainLoader to compose multiple LoaderInterface implementations via explicit ordering.
• Add RegistryInterface::unregisterTool(), unregisterResource(), unregisterResourceTemplate(), unregisterPrompt() — idempotent removals.
• Add RegistryInterface::hasTool(), hasResource(), hasResourceTemplate(), hasPrompt() — by-name existence checks.
• DiscoveryLoader now refreshes only its own previously written entries; manual registrations (via Builder::addTool() etc. or runtime $registry->registerTool() calls) survive rediscovery, and a same-name manual registration takes precedence over discovery on collision.
• [BC Break] Removed ElementReference::$isManual public property and the bool $isManual parameter from all *Reference constructors. Origin tracking is no longer carried on the element; manual-over-discovered precedence is encoded by loader execution order.
• [BC Break] RegistryInterface::registerTool(), registerResource(), registerResourceTemplate(), registerPrompt() lost their trailing bool $isManual = false parameter. Callers using positional arguments must drop the flag.
• [BC Break] Removed RegistryInterface::clear(), getDiscoveryState(), setDiscoveryState(). Rediscovery now goes through DiscoveryLoader::load() directly.
• Registry::register*() semantics changed to plain last-write-wins (overwrites silently) and the methods now return the stored *Reference. The previous "discovered registration is ignored when a manual one already exists" precedence rule still applies, but is now enforced by DiscoveryLoader via reference-identity tracking — and still emits a debug log when a discovery is skipped due to a conflicting registration.
• Add optional title parameter to Builder::addResource() and Builder::addResourceTemplate() for MCP spec compliance
• [BC Break] Builder::addResource() signature changed — $title parameter added between $name and $description. Callers using positional arguments must switch to named arguments.
• [BC Break] Builder::addResourceTemplate() signature changed — $title parameter added between $name and $description. Callers using positional arguments must switch to named arguments.
• Add CorsMiddleware, DnsRebindingProtectionMiddleware, and ProtocolVersionMiddleware for StreamableHttpTransport, composed automatically as the default stack via StreamableHttpTransport::defaultMiddleware()
• [BC BREAK] StreamableHttpTransport constructor: $corsHeaders parameter removed; CORS is now configured via CorsMiddleware. The $middleware parameter is nullable — null (or omitted) installs the default stack; [] disables all defaults. Default Access-Control-Allow-Origin is no longer set (was *).
• [BC Break] ResourceDefinition::__construct() signature changed — $title parameter added between $name and $description. Callers using positional arguments must switch to named arguments.
• [BC Break] ResourceTemplate::__construct() signature changed — $title parameter added between $name and $description. Callers using positional arguments must switch to named arguments.
• [BC Break] McpResource and McpResourceTemplate attribute signatures changed — $title parameter added between $name and $description. Callers using positional arguments must switch to named arguments.

0.5.0

• Add built-in authentication middleware for HTTP transport using OAuth
• Add client component for building MCP clients
• Add Builder::setReferenceHandler() to allow custom ReferenceHandlerInterface implementations (e.g. authorization decorators)
• Add elicitation enum schema types per SEP-1330: TitledEnumSchemaDefinition, MultiSelectEnumSchemaDefinition, TitledMultiSelectEnumSchemaDefinition
• [BC break] Make Symfony Finder component optional. Users would need to install symfony/finder now themselves
• Add LenientOidcDiscoveryMetadataPolicy for identity providers that omit code_challenge_methods_supported (e.g. FusionAuth, Microsoft Entra ID)
• Add OAuth 2.0 Dynamic Client Registration middleware (RFC 7591)
• Add optional title field to Prompt and McpPrompt for MCP spec compliance
• [BC Break] Builder::addPrompt() signature changed — $title parameter added between $name and $description. Callers using positional arguments for $description must switch to named arguments.
• Add optional title field to Tool and McpTool for MCP spec compliance
• [BC Break] Tool::__construct() signature changed — $title parameter added between $name and $inputSchema. Callers using positional arguments must switch to named arguments or pass null for $title.
• [BC Break] McpTool attribute signature changed — $title parameter added between $name and $description. Callers using positional arguments for $description must switch to named arguments.
• [BC Break] Builder::addTool() signature changed — $title parameter added between $name and $description. Callers using positional arguments for $description must switch to named arguments.

0.4.0

• Rename Mcp\Server\Session\Psr16StoreSession to Mcp\Server\Session\Psr16SessionStore
• Add missing handlers for resource subscribe/unsubscribe and persist subscriptions via session
• Introduce SessionManager to encapsulate session handling (replaces SessionFactory) and move garbage collection logic from Protocol.

0.3.0

• Add output schema support to MCP tools
• Add validation of the input parameters given to a Tool.
• Rename Mcp\Capability\Registry\ResourceReference::$schema to Mcp\Capability\Registry\ResourceReference::$resource.
• Introduce SchemaGeneratorInterface and DiscovererInterface to allow custom schema generation and discovery implementations.
• Remove DocBlockParser::getSummary() method, use DocBlockParser::getDescription() instead.

0.2.2

• Throw exception when trying to inject parameter with the unsupported names $_session or $_request.
• Throwable objects are passed to log context instead of the exception message.

0.2.1

• Add RunnerControl for StdioTransport to allow break out from continuously listening for new input.
• Open range of supported Symfony versions to include v5.4

0.2.0

• Make Protocol stateless by decouple if from TransportInterface. Removed Protocol::getTransport().
• Change signature of Builder::addLoaders(...$loaders) to Builder::addLoaders(iterable $loaders).
• Removed ClientAwareInterface in favor of injecting a RequestContext with argument injection.
• The ClientGateway cannot be injected with argument injection anymore. Use RequestContext instead.
• Removed ClientAwareTrait
• Removed Protocol::getTransport()
• Added parameter for TransportInterface to Protocol::processInput()

0.1.0

• First tagged release of package
• Support for implementing MCP server