gopls/internal/mcp: use official go mcp sdk

The gopls MCP server currently uses an internal version
of the Go MCP sdk. This CL updates it to use the official
version at https://github.com/modelcontextprotocol/go-sdk

Change-Id: I35bccd47b6fbb85aaf03f2d00283e07def9ce0f9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/700901
Reviewed-by: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: madelinekalil

gopls/go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/fsnotify/fsnotify v1.9.0
 	github.com/google/go-cmp v0.7.0
 	github.com/jba/templatecheck v0.7.1
+	github.com/modelcontextprotocol/go-sdk v0.4.0
 	golang.org/x/mod v0.27.0
 	golang.org/x/sync v0.16.0
 	golang.org/x/telemetry v0.0.0-20250807160809-1a19826ec488
@@ -23,7 +24,9 @@ require (
 	github.com/BurntSushi/toml v1.5.0 // indirect
 	github.com/fatih/camelcase v1.0.0 // indirect
 	github.com/fatih/structtag v1.2.0 // indirect
+	github.com/google/jsonschema-go v0.2.1-0.20250825175020-748c325cec76 // indirect
 	github.com/google/safehtml v0.1.0 // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	golang.org/x/exp/typeparams v0.0.0-20250718183923-645b1fa84792 // indirect
 	golang.org/x/sys v0.35.0 // indirect
 	golang.org/x/tools/go/expect v0.1.1-deprecated // indirect

gopls/go.sum

@@ -13,6 +13,8 @@ github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZs
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/google/jsonschema-go v0.2.1-0.20250825175020-748c325cec76 h1:mBlBwtDebdDYr+zdop8N62a44g+Nbv7o2KjWyS1deR4=
+github.com/google/jsonschema-go v0.2.1-0.20250825175020-748c325cec76/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
 github.com/google/safehtml v0.1.0 h1:EwLKo8qawTKfsi0orxcQAZzu07cICaBeFMegAU9eaT8=
 github.com/google/safehtml v0.1.0/go.mod h1:L4KWwDsUJdECRAEpZoBn3O64bQaywRscowZjJAzjHnU=
 github.com/jba/templatecheck v0.7.1 h1:yOEIFazBEwzdTPYHZF3Pm81NF1ksxx1+vJncSEwvjKc=
@@ -21,8 +23,12 @@ github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
+github.com/modelcontextprotocol/go-sdk v0.4.0 h1:RJ6kFlneHqzTKPzlQqiunrz9nbudSZcYLmLHLsokfoU=
+github.com/modelcontextprotocol/go-sdk v0.4.0/go.mod h1:whv0wHnsTphwq7CTiKYHkLtwLC06WMoY2KpO+RB9yXQ=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
+github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
+github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
 golang.org/x/crypto v0.39.0/go.mod h1:L+Xg3Wf6HoL4Bn4238Z6ft6KfEpN0tJGo53AAPC632U=

gopls/internal/licenses/licenses.go

@@ -204,6 +204,82 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+-- github.com/google/jsonschema-go LICENSE --
+
+MIT License
+
+Copyright (c) 2025 JSON Schema Go Project Authors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+-- github.com/modelcontextprotocol/go-sdk LICENSE --
+
+MIT License
+
+Copyright (c) 2025 Go MCP SDK Authors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+-- github.com/yosida95/uritemplate/v3 LICENSE --
+
+Copyright (C) 2016, Kohei YOSHIDA <https://yosida95.com/>. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the copyright holder nor the names of its
+      contributors may be used to endorse or promote products derived from
+      this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 -- honnef.co/go/tools LICENSE --
 
 Copyright (c) 2016 Dominik Honnef

gopls/internal/mcp/context.go

@@ -16,6 +16,7 @@ import (
 	"slices"
 	"strings"
 
+	"github.com/modelcontextprotocol/go-sdk/mcp"
 	"golang.org/x/tools/gopls/internal/cache"
 	"golang.org/x/tools/gopls/internal/cache/metadata"
 	"golang.org/x/tools/gopls/internal/cache/parsego"
@@ -24,39 +25,27 @@ import (
 	"golang.org/x/tools/gopls/internal/protocol"
 	"golang.org/x/tools/internal/analysisinternal"
 	"golang.org/x/tools/internal/astutil"
-	"golang.org/x/tools/internal/mcp"
 )
 
 type ContextParams struct {
-	File string `json:"file"`
+	File string `json:"file" jsonschema:"the absolute path to the file"`
 }
 
-func (h *handler) contextTool() *mcp.ServerTool {
-	return mcp.NewServerTool(
-		"go_context",
-		"Provide context for a region within a Go file",
-		h.contextHandler,
-		mcp.Input(
-			mcp.Property("file", mcp.Description("the absolute path to the file")),
-		),
-	)
-}
-
-func (h *handler) contextHandler(ctx context.Context, _ *mcp.ServerSession, params *mcp.CallToolParamsFor[ContextParams]) (*mcp.CallToolResultFor[any], error) {
-	fh, snapshot, release, err := h.fileOf(ctx, params.Arguments.File)
+func (h *handler) contextHandler(ctx context.Context, req *mcp.CallToolRequest, params ContextParams) (*mcp.CallToolResult, any, error) {
+	fh, snapshot, release, err := h.fileOf(ctx, params.File)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	defer release()
 
 	// TODO(hxjiang): support context for GoMod.
 	if snapshot.FileKind(fh) != file.Go {
-		return nil, fmt.Errorf("can't provide context for non-Go file")
+		return nil, nil, fmt.Errorf("can't provide context for non-Go file")
 	}
 
 	pkg, pgf, err := golang.NarrowestPackageForFile(ctx, snapshot, fh.URI())
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	var result strings.Builder
@@ -67,7 +56,7 @@ func (h *handler) contextHandler(ctx context.Context, _ *mcp.ServerSession, para
 		fmt.Fprintf(&result, "%s (current file):\n", pgf.URI.Base())
 		result.WriteString("```go\n")
 		if err := writeFileSummary(ctx, snapshot, pgf.URI, &result, false, nil); err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 		result.WriteString("```\n\n")
 	}
@@ -82,7 +71,7 @@ func (h *handler) contextHandler(ctx context.Context, _ *mcp.ServerSession, para
 			fmt.Fprintf(&result, "%s:\n", file.URI.Base())
 			result.WriteString("```go\n")
 			if err := writeFileSummary(ctx, snapshot, file.URI, &result, false, nil); err != nil {
-				return nil, err
+				return nil, nil, err
 			}
 			result.WriteString("```\n\n")
 		}
@@ -104,7 +93,7 @@ func (h *handler) contextHandler(ctx context.Context, _ *mcp.ServerSession, para
 
 				text, err := pgf.NodeText(genDecl)
 				if err != nil {
-					return nil, err
+					return nil, nil, err
 				}
 
 				result.Write(text)
@@ -144,7 +133,7 @@ func (h *handler) contextHandler(ctx context.Context, _ *mcp.ServerSession, para
 		}
 	}
 
-	return textResult(result.String()), nil
+	return textResult(result.String()), nil, nil
 }
 
 func summarizePackage(ctx context.Context, snapshot *cache.Snapshot, md *metadata.Package) string {

gopls/internal/mcp/file_context.go

@@ -11,41 +11,30 @@ import (
 	"go/types"
 	"strings"
 
+	"github.com/modelcontextprotocol/go-sdk/mcp"
 	"golang.org/x/tools/gopls/internal/golang"
 	"golang.org/x/tools/gopls/internal/protocol"
-	"golang.org/x/tools/internal/mcp"
 )
 
 type fileContextParams struct {
-	File string `json:"file"`
+	File string `json:"file" jsonschema:"the absolute path to the file"`
 }
 
-func (h *handler) fileContextTool() *mcp.ServerTool {
-	return mcp.NewServerTool(
-		"go_file_context",
-		"Summarizes a file's cross-file dependencies",
-		h.fileContextHandler,
-		mcp.Input(
-			mcp.Property("file", mcp.Description("the absolute path to the file")),
-		),
-	)
-}
-
-func (h *handler) fileContextHandler(ctx context.Context, _ *mcp.ServerSession, params *mcp.CallToolParamsFor[fileContextParams]) (*mcp.CallToolResultFor[any], error) {
-	fh, snapshot, release, err := h.fileOf(ctx, params.Arguments.File)
+func (h *handler) fileContextHandler(ctx context.Context, req *mcp.CallToolRequest, params fileContextParams) (*mcp.CallToolResult, any, error) {
+	fh, snapshot, release, err := h.fileOf(ctx, params.File)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	defer release()
 
 	pkg, pgf, err := golang.NarrowestPackageForFile(ctx, snapshot, fh.URI())
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	info := pkg.TypesInfo()
 	if info == nil {
-		return nil, fmt.Errorf("no types info for package %q", pkg.Metadata().PkgPath)
+		return nil, nil, fmt.Errorf("no types info for package %q", pkg.Metadata().PkgPath)
 	}
 
 	// Group objects defined in other files by file URI.
@@ -79,26 +68,26 @@ func (h *handler) fileContextHandler(ctx context.Context, _ *mcp.ServerSession,
 	}
 
 	var result strings.Builder
-	fmt.Fprintf(&result, "File `%s` is in package %q.\n", params.Arguments.File, pkg.Metadata().PkgPath)
+	fmt.Fprintf(&result, "File `%s` is in package %q.\n", params.File, pkg.Metadata().PkgPath)
 	fmt.Fprintf(&result, "Below is a summary of the APIs it uses from other files.\n")
 	fmt.Fprintf(&result, "To read the full API of any package, use go_package_api.\n")
 	for uri, decls := range otherFiles {
 		pkgPath := "UNKNOWN"
 		md, err := snapshot.NarrowestMetadataForFile(ctx, uri)
 		if err != nil {
 			if ctx.Err() != nil {
-				return nil, ctx.Err()
+				return nil, nil, ctx.Err()
 			}
 		} else {
 			pkgPath = string(md.PkgPath)
 		}
 		fmt.Fprintf(&result, "Referenced declarations from %s (package %q):\n", uri.Path(), pkgPath)
 		result.WriteString("```go\n")
 		if err := writeFileSummary(ctx, snapshot, uri, &result, false, decls); err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 		result.WriteString("```\n\n")
 	}
 
-	return textResult(result.String()), nil
+	return textResult(result.String()), nil, nil
 }

gopls/internal/mcp/file_diagnostics.go

@@ -20,46 +20,36 @@ import (
 	"golang.org/x/tools/gopls/internal/golang"
 	"golang.org/x/tools/gopls/internal/protocol"
 	"golang.org/x/tools/internal/diff"
-	"golang.org/x/tools/internal/mcp"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
 )
 
 type diagnosticsParams struct {
-	File string `json:"file"`
-}
-
-func (h *handler) fileDiagnosticsTool() *mcp.ServerTool {
-	return mcp.NewServerTool(
-		"go_file_diagnostics",
-		"Provides diagnostics for a Go file",
-		h.fileDiagnosticsHandler,
-		mcp.Input(
-			mcp.Property("file", mcp.Description("the absolute path to the file to diagnose")),
-		),
-	)
+	File string `json:"file" jsonschema:"the absolute path to the file to diagnose"`
 }
 
-func (h *handler) fileDiagnosticsHandler(ctx context.Context, _ *mcp.ServerSession, params *mcp.CallToolParamsFor[diagnosticsParams]) (*mcp.CallToolResultFor[any], error) {
-	fh, snapshot, release, err := h.fileOf(ctx, params.Arguments.File)
+func (h *handler) fileDiagnosticsHandler(ctx context.Context, req *mcp.CallToolRequest, params diagnosticsParams) (*mcp.CallToolResult, any, error) {
+	fh, snapshot, release, err := h.fileOf(ctx, params.File)
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 	defer release()
 
 	diagnostics, fixes, err := h.diagnoseFile(ctx, snapshot, fh.URI())
 	if err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	var builder strings.Builder
 	if len(diagnostics) == 0 {
-		return textResult("No diagnostics"), nil
+		return textResult("No diagnostics"), nil, nil
 	}
 
 	if err := summarizeDiagnostics(ctx, snapshot, &builder, diagnostics, fixes); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
-	return textResult(builder.String()), nil
+	return textResult(builder.String()), nil, nil
 }
 
 // diagnoseFile diagnoses a single file, including go/analysis and quick fixes.