* Address review feedback on resource_link
Three follow-ups from review of the resource_link work:
* PromptResultFormatter: add a regression test proving the optional
fields of a typed resource_link block (title, description, mimeType,
size, annotations, _meta) survive formatting. The delegation to
ResourceLink::fromArray() already landed while rebasing onto the
PromptResultFormatter refactor, but the existing test only supplied
uri/name and so could not catch a reintroduced field drop.
* ResourceLink::fromArray(): validate optional fields consistently, the
way the equivalent ResourceDefinition::fromArray() already does.
description, mimeType and size now raise InvalidArgumentException
instead of surfacing a TypeError (or silently coercing, for size's
(int) cast); annotations goes through Annotations::tryFromArray(),
which carries the is_array() guard that icons already had; icons uses
Icon::listFromArray() so a non-array entry is reported in context.
* ToolReference::extractStructuredContent(): never emit a list as
structuredContent. The Content guard added earlier fixed only one
instance of the real invariant - structuredContent must be a JSON
object, and a PHP list can never be one. Tool::fromArray() already
enforces the matching rule by rejecting an outputSchema whose type is
not "object", so this aligns the runtime path with it. The test
asserting the opposite for an array-typed outputSchema contradicted
the phpstan type and the fromArray() check introduced alongside it in
the same commit, so it is replaced by tests for the two list shapes.
* Apply the structuredContent object rule to object results too
`extractStructuredContent()` guards raw array results against being emitted
as a JSON array, but the object branch handed back whatever `json_decode()`
produced. A `JsonSerializable` returning a list or a scalar slipped straight
through, producing exactly the `structuredContent` the array guard exists to
prevent — and a return value that contradicts the method's own
`array<string, mixed>|null` signature.
Check the decoded value before returning it, and cover the object branch,
which had no tests at all.
* Document structured tool output
`outputSchema` and `structuredContent` were undocumented: the tool return
value docs covered only the `content` side, and the schema generation
section is about tool parameters.
Add a "Structured Output" subsection covering how to declare the schema,
which return values populate `structuredContent`, and why a list has to be
wrapped in a key to get structured output at all.
* Gate structuredContent on the negotiated protocol revision
SEP-2106 (revision 2026-07-28) widens structuredContent to any JSON value;
earlier revisions require an object. Resolve the revision per request and
apply the matching rule, and warn when a declared outputSchema yields none.
* Resolve the protocol revision on RequestContext
Keeps the `_meta`-then-session lookup in one place instead of per handler,
and exposes the negotiated revision to tool handlers.
* Document reading the negotiated revision from RequestContext
* Warn when a self-built CallToolResult carries an invalid structuredContent
Returning a CallToolResult opts out of the extraction rules, so the value is
still sent unchanged — but a JSON array is not valid before SEP-2106.
* Add resource_link content block
The spec's `resource_link` content type (protocol revision 2025-06-18,
still present in 2025-11-25) had no corresponding schema class: it lets a
tool result or prompt message reference a resource by URI/name without
embedding its full contents, the way `EmbeddedResource` does. Without it,
tools returning many or large resource references (e.g. search results
over a DAM) are stuck smuggling URIs through text/structured content.
Add `Mcp\Schema\Content\ResourceLink`, mirroring the spec's `Resource`
shape (uri, name, title, description, mimeType, annotations, size, icons,
_meta) with a fixed `type: "resource_link"`, following the conventions of
the sibling `EmbeddedResource`/`ResourceDefinition` classes.
Register it everywhere `resource` content blocks are (de)serialized by
type per the spec's `ContentBlock` union:
- `CallToolResult::fromArray()`
- `PromptMessage` (constructor type, `fromArray()`, phpstan types)
- `PromptResultFormatter` (typed-array and direct-instance paths)
`SamplingMessage`/`CreateSamplingMessageResult` are intentionally left
unchanged: the spec's `SamplingMessageContentBlock` does not include
`ResourceLink`.
Fixes#399
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* Add resource_link example coverage to discovery-userprofile
Add a lookup_user tool to the discovery-userprofile example: given a
userId, it returns a short text summary plus a resource_link pointing
at the existing user://{userId}/profile resource template, instead of
embedding the profile. This mirrors the PR's motivating use case (a
tool referencing many/large resources by URI rather than inlining
them) and exercises resource_link through the example's own inspector
snapshot tests (tools_call-lookup_user[_not_found], tools_list).
Wiring this up surfaced a real bug: ToolReference::extractStructuredContent()
passed any raw array return value straight through as structuredContent,
even when it held Content instances (e.g. the TextContent/ResourceLink
pair above). That serializes to a JSON list, which fails the spec's
requirement that structuredContent be an object - the inspector's MCP
client rejected the tool call outright until fixed. Skip structuredContent
extraction whenever the raw result contains a Content item, since those
are already represented in `content` and were never meant to double as
structured data.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---------
Co-authored-by: Alex Rothberg <51059+cancan101@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Wrap-up for the v0.6.0 release: capture features/BC breaks merged since
v0.5.0 that were missing from documentation.
- CHANGELOG: add the `title` field on `Resource`/`ResourceTemplate` (#301),
a feature plus three positional-argument BC breaks.
- mcp-elements.md: add the missing `title` parameter to the McpTool,
McpResource, McpResourceTemplate and McpPrompt attribute reference
sections; fix a missing closing paren in an `#[McpPrompt]` example.
- server-builder.md: add `title?` to the `addPrompt()` row of the method
reference table (stale since v0.5.0).
- client.md: bump the protocol-version example to `V2025_11_25` to match
the new default.
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
* [Server] feat: allow runtime handlers
Adds Mcp\Server\Handler\RunTimeHandlerInterface so integrators
(e.g. configuration-driven element sources) can register handlers
whose arguments and execution are resolved at runtime rather than
via PHP reflection of a callable.
ReferenceHandler::handle() dispatches instanceof RunTimeHandler
ahead of the callable/array/string branches, calls filterArguments
to narrow the argument map, and forwards execute() a ClientGateway
built from the active session.
The Registry-layer surface (ElementReference and the four
*Reference subclasses, RegistryInterface, Registry::register*,
ArrayLoader's handler-description helper) is widened to accept the
new type. The Builder/ArrayLoader path keeps its narrow callable
union; exposing runtime handlers there requires reworking
HandlerResolver and is left for a follow-up.
* feat(server): add runtime handler metadata API
Extend RunTimeHandlerInterface with four nullable metadata
accessors (getInputSchema, getOutputSchema, getPromptArguments,
getCompletionProviders) so the loader can obtain element
metadata without reflection.
Add RunTimeHandlerTrait providing null defaults for all four
accessors so single-purpose handlers can override only the
methods relevant to their element kind.
* feat(server): expose runtime handlers via Builder
Widen Builder::addTool, addResource, addResourceTemplate, and
addPrompt to accept RunTimeHandlerInterface instances alongside
the existing closure/array/string handler forms.
Branch ArrayLoader::load() on instanceof RunTimeHandlerInterface
in each of the four registration loops so runtime handlers skip
the reflection-based HandlerResolver/HandlerSchema path and pull
metadata from the interface accessors instead. Require explicit
name and description for runtime handlers and raise
ConfigurationException when missing or when a runtime tool has
no input schema source.
Replace direct $data['handler'] use in error log context with
getHandlerDescription() to avoid serializing large runtime
handler object graphs into log records.
Document the runtime handler API in docs/server-builder.md with a
new Runtime Handlers subsection and add a cross-reference from
docs/mcp-elements.md.
* test(server): cover runtime handler Builder path
Add ArrayLoaderRunTimeHandlerTest covering:
- successful tool registration with handler-supplied input schema,
with kwarg input schema (precedence over the handler), and the
same precedence rule for output schema
- ConfigurationException for tools missing name, description, or
any input schema source
- successful resource registration via Builder kwargs and the
matching missing-name failure mode
- successful resource template registration with completion
providers sourced from the handler and the missing-description
failure mode
- successful prompt registration with arguments and completion
providers sourced from the handler, plus the missing-name
failure mode
- a trait-only fixture verifying the four metadata accessors
return null by default
Update existing ReferenceHandlerTest anonymous classes to use
RunTimeHandlerTrait so they satisfy the widened interface.
* refactor(server): split runtime handler interface
Splits RunTimeHandlerInterface into a minimal base contract (only
execute()) plus element-specific subtypes: RunTimeToolHandlerInterface,
RunTimePromptHandlerInterface, and
RunTimeResourceTemplateHandlerInterface. Each subtype declares only
the metadata accessors relevant to its element kind, so a tool
handler no longer has to no-op out prompt or template methods.
Drops the now-redundant RunTimeHandlerTrait and removes
filterArguments; execute() receives the full argument map directly.
Updates ArrayLoader, ReferenceHandler, and Builder type signatures
to use the per-element interfaces, and rewrites the Runtime
Handlers documentation accordingly.
* refactor(server): rename runtime handler interfaces to Runtime casing
Renames RunTimeHandlerInterface and its element-specific subtypes to
Runtime casing, adds a dedicated RuntimeResourceHandlerInterface so
addResource() rejects mismatched runtime handlers at the type level,
and strips _session and _request from arguments forwarded to runtime
handlers. Hardens ArrayLoader to re-throw ConfigurationException
without wrapping, and extracts inline test fixtures into
tests/Fixtures/Runtime/.
* chore: please the linting gods
* test(server): use Uuid::v4 for symfony/uid 5.4 compatibility
Uuid::v7() was added in symfony/uid 6.2 and breaks the Symfony 5.4
matrix job. Match the convention used elsewhere in the suite.
* refactor(server): split ArrayLoader registration
Extract per-element preparation into dedicated private prepare*
methods for tools, resources, templates, and prompts. Factor the
shared required-field assertion and reflected name/description
resolution into helpers.
* refactor(server): non-null runtime handler types
Drop nullable return types on RuntimeToolHandlerInterface::
getInputSchema(), RuntimePromptHandlerInterface::
getPromptArguments()/getCompletionProviders(), and
RuntimeResourceTemplateHandlerInterface::
getCompletionProviders() in favor of plain arrays.
ArrayLoader no longer needs the null-coalescing
fallbacks, and NullSchemaToolHandler plus its
ConfigurationException test become redundant.
* doc: update docs/server-builder.md
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
* feat: peer revie feedback
Introduce a new `Builder::add(...)` pattern for a more generic runtime
handler.
* refactor(server): apply PR 294 review feedback
Move per-interface handler dispatch from ReferenceHandler into
ExplicitElementLoader by wrapping each ElementHandlerInterface in a
Closure that satisfies the existing callable contract, revert the
*Reference / Registry handler-type widening PR 294 introduced, throw
Mcp\Exception\InvalidArgumentException (not \TypeError) on mismatched
Builder::add() pairings, and rename two classes for clarity:
* Mcp\Capability\Registry\Loader\ArrayLoader -> ReflectedElementLoader
* Mcp\Schema\Resource -> Mcp\Schema\ResourceDefinition (no alias)
ReferenceHandler::prepareArguments() now injects ClientGateway by type
and binds an `array $arguments` / `array $variables` closure parameter
from the leftover inbound arguments. This addresses Antoine's coupling
concern (ReferenceHandler no longer knows about the four handler
interfaces) and Chris's package-exception preference, and clears the
phpdoc reserved-word collision Antoine flagged on the resource schema
class. Existing tests are re-targeted to exercise the closure path
through ExplicitElementLoader / ReferenceHandler.
* doc: address PR 294 review feedback
Apply Chris's line-level suggestions on docs/server-builder.md
(rewrap to 120 chars, smoothed Drupal mcp module name-drop in the
explicit-element registration section, exception name reads
Mcp\Exception\InvalidArgumentException), rewrap docs/mcp-elements.md
to 120 chars, and add 0.6.0 CHANGELOG entries covering the
Builder::add() entry point, the new handler interfaces, the new
ExplicitElementLoader, plus three BC breaks (Resource ->
ResourceDefinition rename, ArrayLoader -> ReflectedElementLoader
rename, mismatched-pairing exception swap).
* refactor: address self-review feedback
* CHANGELOG: drop spurious [BC Break] entry for the exception
type Builder::add() raises (method is new in this PR).
* docs/server-builder: revert wrap-only edits to pre-existing
main content; keep 120ch wrapping only for new sections.
* ExplicitElementLoader: trim verbose class docblock.
* ReferenceHandler: rename SPLAT_PARAMETER_NAMES constant to
ARGUMENT_BAG_PARAMETERS.
* refactor: rename CallableHandler to Handler
* style: fix phpdoc param alignment
* refactor: inline $reference->handler access
* fix: maintainer review feedback
docs: mention ExplicitElementLoader in comment
docs: move Drupal reference to README list
docs: drop implementation-only changelog entry
docs: revert rewrap noise from mcp-elements.md
* style: fix phpdoc param alignment
---------
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
Co-authored-by: soyuka <soyuka@users.noreply.github.com>
* fix: standardize error handling across handlers with MCP specification compliance
* Update mcp-elements.md
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
* docs: clarify error handling behavior for all element types
* docs: remove unnecessary whitespace in mcp-elements.md
* fix: simplify exception signatures to accept simple messages
* refactor: use specific exceptions in examples for better error handling
* feat: throw exceptions from reference provider instead of returning null
---------
Co-authored-by: Christopher Hertel <mail@christopher-hertel.de>
* docs: add more about building servers and updating front readme
* Overhaul documentation structure and content
* fix: remove redundant emoji on docs
* Remove composer install --dev hint
* Add linebreak to make it readable in IDE
* rebase after example renaming
---------
Co-authored-by: Kyrian Obikwelu <koshnawaza@gmail.com>
