feat(go): add MCP plugin support for resources

go/core/resource/matcher.go

@@ -18,6 +18,7 @@ package resource
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/yosida95/uritemplate/v3"
 )
@@ -29,6 +30,30 @@ type URIMatcher interface {
 	ExtractVariables(uri string) (map[string]string, error)
 }
 
+// normalizeURI cleans up a URI for template matching by removing common user issues:
+// - Query parameters: "api://search/hello?limit=10" → "api://search/hello"
+// - Trailing slashes: "api://users/123/" → "api://users/123"
+// - URI fragments: "docs://page/intro#section1" → "docs://page/intro"
+// This improves user experience by making template matching more forgiving.
+func normalizeURI(uri string) string {
+	// Remove query parameters
+	if idx := strings.Index(uri, "?"); idx != -1 {
+		uri = uri[:idx]
+	}
+
+	// Remove URI fragments
+	if idx := strings.Index(uri, "#"); idx != -1 {
+		uri = uri[:idx]
+	}
+
+	// Remove trailing slash (but keep if it's just the root "/")
+	if len(uri) > 1 && strings.HasSuffix(uri, "/") {
+		uri = uri[:len(uri)-1]
+	}
+
+	return uri
+}
+
 // NewStaticMatcher creates a matcher for exact URI matches.
 func NewStaticMatcher(uri string) URIMatcher {
 	return &staticMatcher{uri: uri}
@@ -65,12 +90,14 @@ type templateMatcher struct {
 }
 
 func (m *templateMatcher) Matches(uri string) bool {
-	values := m.template.Match(uri)
+	cleanURI := normalizeURI(uri)
+	values := m.template.Match(cleanURI)
 	return len(values) > 0
 }
 
 func (m *templateMatcher) ExtractVariables(uri string) (map[string]string, error) {
-	values := m.template.Match(uri)
+	cleanURI := normalizeURI(uri)
+	values := m.template.Match(cleanURI)
 	if len(values) == 0 {
 		return nil, fmt.Errorf("URI %q does not match template", uri)
 	}

go/genkit/resource.go

@@ -324,3 +324,20 @@ func (d *detachedResourceAction) Register(r *registry.Registry) {
 func (r *resourceAction) Name() string {
 	return r.action.Name()
 }
+
+// ListResources returns a slice of all resource actions
+func ListResources(g *Genkit) []core.Action {
+	acts := g.reg.ListActions()
+	resources := []core.Action{}
+	for _, act := range acts {
+		action, ok := act.(core.Action)
+		if !ok {
+			continue
+		}
+		actionDesc := action.Desc()
+		if actionDesc.Type == core.ActionTypeResource {
+			resources = append(resources, action)
+		}
+	}
+	return resources
+}

go/plugins/mcp/common.go

@@ -17,7 +17,6 @@ package mcp
 
 import (
 	"fmt"
-	"strings"
 
 	"github.com/mark3labs/mcp-go/mcp"
 )
@@ -32,19 +31,9 @@ func (c *GenkitMCPClient) GetToolNameWithNamespace(toolName string) string {
 	return fmt.Sprintf("%s_%s", c.options.Name, toolName)
 }
 
-// ContentToText extracts text content from MCP Content
-func ContentToText(contentList []mcp.Content) string {
-	var textParts []string
-	for _, contentItem := range contentList {
-		if textContent, ok := contentItem.(mcp.TextContent); ok && textContent.Type == "text" {
-			textParts = append(textParts, textContent.Text)
-		} else if erContent, ok := contentItem.(mcp.EmbeddedResource); ok {
-			if trc, ok := erContent.Resource.(mcp.TextResourceContents); ok {
-				textParts = append(textParts, trc.Text)
-			}
-		}
-	}
-	return strings.Join(textParts, "")
+// GetResourceNameWithNamespace returns a resource name prefixed with the client's namespace
+func (c *GenkitMCPClient) GetResourceNameWithNamespace(resourceName string) string {
+	return fmt.Sprintf("%s_%s", c.options.Name, resourceName)
 }
 
 // ExtractTextFromContent extracts text content from MCP Content

go/plugins/mcp/fixtures/basic_server/basic_server.go

@@ -0,0 +1,38 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+
+	"github.com/firebase/genkit/go/ai"
+	"github.com/firebase/genkit/go/core"
+	"github.com/firebase/genkit/go/genkit"
+	"github.com/firebase/genkit/go/plugins/mcp"
+)
+
+func main() {
+	g, _ := genkit.Init(context.Background())
+	genkit.DefineResource(g, genkit.ResourceOptions{
+		Name:     "test-docs",
+		Template: "file://test/{filename}",
+	}, func(ctx context.Context, input core.ResourceInput) (genkit.ResourceOutput, error) {
+		return genkit.ResourceOutput{
+			Content: []*ai.Part{ai.NewTextPart("test content")},
+		}, nil
+	})
+	server := mcp.NewMCPServer(g, mcp.MCPServerOptions{Name: "test"})
+	server.ServeStdio()
+}

go/plugins/mcp/fixtures/content_server/content_server.go

@@ -0,0 +1,44 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/firebase/genkit/go/ai"
+	"github.com/firebase/genkit/go/core"
+	"github.com/firebase/genkit/go/genkit"
+	"github.com/firebase/genkit/go/plugins/mcp"
+)
+
+func main() {
+	g, _ := genkit.Init(context.Background())
+
+	// Resource that provides different content based on filename
+	genkit.DefineResource(g, genkit.ResourceOptions{
+		Name:     "content-provider",
+		Template: "file://data/{filename}",
+	}, func(ctx context.Context, input core.ResourceInput) (genkit.ResourceOutput, error) {
+		filename := input.Variables["filename"]
+		content := fmt.Sprintf("CONTENT_FROM_SERVER: This is %s with important data.", filename)
+		return genkit.ResourceOutput{
+			Content: []*ai.Part{ai.NewTextPart(content)},
+		}, nil
+	})
+
+	server := mcp.NewMCPServer(g, mcp.MCPServerOptions{Name: "content-server"})
+	server.ServeStdio()
+}

go/plugins/mcp/fixtures/policy_server/policy_server.go

@@ -0,0 +1,38 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+
+	"github.com/firebase/genkit/go/ai"
+	"github.com/firebase/genkit/go/core"
+	"github.com/firebase/genkit/go/genkit"
+	"github.com/firebase/genkit/go/plugins/mcp"
+)
+
+func main() {
+	g, _ := genkit.Init(context.Background())
+	genkit.DefineResource(g, genkit.ResourceOptions{
+		Name:     "company-policy",
+		Template: "docs://policy/{section}",
+	}, func(ctx context.Context, input core.ResourceInput) (genkit.ResourceOutput, error) {
+		return genkit.ResourceOutput{
+			Content: []*ai.Part{ai.NewTextPart("VACATION_POLICY: Employees get 20 days vacation per year.")},
+		}, nil
+	})
+	server := mcp.NewMCPServer(g, mcp.MCPServerOptions{Name: "test"})
+	server.ServeStdio()
+}

go/plugins/mcp/fixtures/server_a/server_a.go

@@ -0,0 +1,38 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+
+	"github.com/firebase/genkit/go/ai"
+	"github.com/firebase/genkit/go/core"
+	"github.com/firebase/genkit/go/genkit"
+	"github.com/firebase/genkit/go/plugins/mcp"
+)
+
+func main() {
+	g, _ := genkit.Init(context.Background())
+	genkit.DefineResource(g, genkit.ResourceOptions{
+		Name:     "server-a-docs",
+		Template: "a://docs/{file}",
+	}, func(ctx context.Context, input core.ResourceInput) (genkit.ResourceOutput, error) {
+		return genkit.ResourceOutput{
+			Content: []*ai.Part{ai.NewTextPart("Content from Server A")},
+		}, nil
+	})
+	server := mcp.NewMCPServer(g, mcp.MCPServerOptions{Name: "server-a"})
+	server.ServeStdio()
+}

go/plugins/mcp/fixtures/server_b/server_b.go

@@ -0,0 +1,38 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+
+	"github.com/firebase/genkit/go/ai"
+	"github.com/firebase/genkit/go/core"
+	"github.com/firebase/genkit/go/genkit"
+	"github.com/firebase/genkit/go/plugins/mcp"
+)
+
+func main() {
+	g, _ := genkit.Init(context.Background())
+	genkit.DefineResource(g, genkit.ResourceOptions{
+		Name:     "server-b-files",
+		Template: "b://files/{path}",
+	}, func(ctx context.Context, input core.ResourceInput) (genkit.ResourceOutput, error) {
+		return genkit.ResourceOutput{
+			Content: []*ai.Part{ai.NewTextPart("Content from Server B")},
+		}, nil
+	})
+	server := mcp.NewMCPServer(g, mcp.MCPServerOptions{Name: "server-b"})
+	server.ServeStdio()
+}