Make search_issues semantic by default

README.md

@@ -976,7 +976,7 @@ The following sets of tools are available:
   - `owner`: Optional repository owner. If provided with repo, only issues for this repository are listed. (string, optional)
   - `page`: Page number for pagination (min 1) (number, optional)
   - `perPage`: Results per page for pagination (min 1, max 100) (number, optional)
-  - `query`: Search query using GitHub issues search syntax (string, required)
+  - `query`: The search query, as natural language. When the user gives alternative wordings, include them as plain words rather than joining them with OR. (string, required)
   - `repo`: Optional repository name. If provided with owner, only issues for this repository are listed. (string, optional)
   - `sort`: Sort field by number of matches of categories, defaults to best match (string, optional)
 

internal/ghmcp/server.go

@@ -138,6 +138,11 @@ func NewStdioMCPServer(ctx context.Context, cfg github.MCPServerConfig) (*mcp.Se
 		return nil, fmt.Errorf("failed to parse API host: %w", err)
 	}
 
+	hostType, err := utils.ParseHostType(cfg.Host)
+	if err != nil {
+		return nil, fmt.Errorf("failed to classify API host: %w", err)
+	}
+
 	clients, err := createGitHubClients(cfg, apiHost)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create GitHub clients: %w", err)
@@ -165,7 +170,7 @@ func NewStdioMCPServer(ctx context.Context, cfg github.MCPServerConfig) (*mcp.Se
 		obs,
 	)
 	// Build and register the tool/resource/prompt inventory
-	inventoryBuilder := github.NewInventory(cfg.Translator).
+	inventoryBuilder := github.NewInventory(cfg.Translator, github.WithHost(hostType)).
 		WithDeprecatedAliases(github.DeprecatedToolAliases).
 		WithReadOnly(cfg.ReadOnly).
 		WithToolsets(github.ResolvedEnabledToolsets(cfg.EnabledToolsets, cfg.EnabledTools)).

pkg/github/__toolsnaps__/search_issues.snap

@@ -4,7 +4,7 @@
     "readOnlyHint": true,
     "title": "Search issues"
   },
-  "description": "Search for issues in GitHub repositories using issues search syntax already scoped to is:issue",
+  "description": "Search issues using natural-language semantic matching. Best for conceptual or paraphrased queries (e.g. \"login fails after password reset\"). Already scoped to is:issue.",
   "inputSchema": {
     "properties": {
       "fields": {
@@ -64,7 +64,7 @@
         "type": "number"
       },
       "query": {
-        "description": "Search query using GitHub issues search syntax",
+        "description": "The search query, as natural language. When the user gives alternative wordings, include them as plain words rather than joining them with OR.",
         "type": "string"
       },
       "repo": {

pkg/github/inventory.go

@@ -10,9 +10,9 @@ import (
 // This function is stateless - no dependencies are captured.
 // Handlers are generated on-demand during registration via RegisterAll(ctx, server, deps).
 // The "default" keyword in WithToolsets will expand to toolsets marked with Default: true.
-func NewInventory(t translations.TranslationHelperFunc) *inventory.Builder {
+func NewInventory(t translations.TranslationHelperFunc, opts ...ToolOption) *inventory.Builder {
 	return inventory.NewBuilder().
-		SetTools(AllTools(t)).
+		SetTools(AllTools(t, opts...)).
 		SetResources(AllResources(t)).
 		SetPrompts(AllPrompts(t))
 }

pkg/github/issues.go

@@ -1595,14 +1595,43 @@ func ReprioritizeSubIssue(ctx context.Context, client *github.Client, owner stri
 	return utils.NewToolResultText(string(r)), nil
 }
 
+// The two search engines want opposite things from a caller, so steering advice
+// for one is counterproductive for the other: semantic rewards paraphrased
+// natural language and degrades on boolean operators, while lexical needs the
+// caller's literal keywords and handles OR fine. The description has to describe
+// the engine the host will actually use.
+const (
+	searchIssuesSemanticDescription = "Search issues using natural-language semantic matching. Best for conceptual or paraphrased queries (e.g. \"login fails after password reset\"). Already scoped to is:issue."
+	searchIssuesLexicalDescription  = "Search for issues in GitHub repositories using issues search syntax already scoped to is:issue"
+
+	searchIssuesSemanticQueryDescription = "The search query, as natural language. When the user gives alternative wordings, include them as plain words rather than joining them with OR."
+	searchIssuesLexicalQueryDescription  = "Search query using GitHub issues search syntax"
+)
+
 // SearchIssues creates a tool to search for issues.
-func SearchIssues(t translations.TranslationHelperFunc) inventory.ServerTool {
+func SearchIssues(t translations.TranslationHelperFunc, opts ...ToolOption) inventory.ServerTool {
+	cfg := newToolConfig(opts)
+
+	// Semantic is the default; however as it is not available on GHES, we fall back to
+	// lexical search for that host type.
+	mode := searchModeSemantic
+	if cfg.hostType == utils.HostTypeGHES {
+		mode = searchModeLexical
+	}
+
+	toolDescription := searchIssuesSemanticDescription
+	queryDescription := searchIssuesSemanticQueryDescription
+	if mode == searchModeLexical {
+		toolDescription = searchIssuesLexicalDescription
+		queryDescription = searchIssuesLexicalQueryDescription
+	}
+
 	schema := &jsonschema.Schema{
 		Type: "object",
 		Properties: map[string]*jsonschema.Schema{
 			"query": {
 				Type:        "string",
-				Description: "Search query using GitHub issues search syntax",
+				Description: queryDescription,
 			},
 			"owner": {
 				Type:        "string",
@@ -1647,7 +1676,7 @@ func SearchIssues(t translations.TranslationHelperFunc) inventory.ServerTool {
 		ToolsetMetadataIssues,
 		mcp.Tool{
 			Name:        "search_issues",
-			Description: t("TOOL_SEARCH_ISSUES_DESCRIPTION", "Search for issues in GitHub repositories using issues search syntax already scoped to is:issue"),
+			Description: t("TOOL_SEARCH_ISSUES_DESCRIPTION", toolDescription),
 			Annotations: &mcp.ToolAnnotations{
 				Title:        t("TOOL_SEARCH_ISSUES_USER_TITLE", "Search issues"),
 				ReadOnlyHint: true,
@@ -1662,7 +1691,7 @@ func SearchIssues(t translations.TranslationHelperFunc) inventory.ServerTool {
 				return utils.NewToolResultError(err.Error()), nil, nil
 			}
 			options = append(options, withFieldsFiltering(deps, "search_issues", fields))
-			result, err := searchIssuesHandler(ctx, deps, args, options...)
+			result, err := searchIssuesHandler(ctx, deps, args, mode, options...)
 			return result, nil, err
 		})
 }
@@ -1930,10 +1959,10 @@ func fetchIssueReadEnrichment(ctx context.Context, gqlClient *githubv4.Client, n
 // searchIssuesHandler runs the REST issues search, enriches each hit with custom field values
 // fetched via a single follow-up GraphQL nodes() query, and applies any post-process options
 // (e.g. IFC labelling).
-func searchIssuesHandler(ctx context.Context, deps ToolDependencies, args map[string]any, options ...searchOption) (*mcp.CallToolResult, error) {
+func searchIssuesHandler(ctx context.Context, deps ToolDependencies, args map[string]any, mode searchMode, options ...searchOption) (*mcp.CallToolResult, error) {
 	const errorPrefix = "failed to search issues"
 
-	query, opts, err := prepareSearchArgs(args, "issue")
+	query, opts, err := prepareSearchArgs(args, "issue", mode)
 	if err != nil {
 		return utils.NewToolResultError(err.Error()), nil
 	}

pkg/github/issues_test.go

@@ -870,11 +870,12 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "is:issue repo:owner/repo is:open",
-						"sort":     "created",
-						"order":    "desc",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "is:issue repo:owner/repo is:open",
+						"sort":        "created",
+						"order":       "desc",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -896,11 +897,12 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "repo:test-owner/test-repo is:issue is:open",
-						"sort":     "created",
-						"order":    "asc",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "repo:test-owner/test-repo is:issue is:open",
+						"sort":        "created",
+						"order":       "asc",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -922,9 +924,10 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "is:issue bug",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "is:issue bug",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -943,9 +946,10 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "is:issue feature",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "is:issue feature",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -975,9 +979,10 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "repo:github/github-mcp-server is:issue is:open (label:critical OR label:urgent)",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "repo:github/github-mcp-server is:issue is:open (label:critical OR label:urgent)",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -995,9 +1000,10 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "is:issue repo:github/github-mcp-server critical",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "is:issue repo:github/github-mcp-server critical",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -1017,9 +1023,10 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "is:issue repo:octocat/Hello-World bug",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "is:issue repo:octocat/Hello-World bug",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -1037,9 +1044,10 @@ func Test_SearchIssues(t *testing.T) {
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "repo:github/github-mcp-server is:issue (label:critical OR label:urgent OR label:high-priority OR label:blocker)",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "repo:github/github-mcp-server is:issue (label:critical OR label:urgent OR label:high-priority OR label:blocker)",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),
@@ -1060,6 +1068,7 @@ func Test_SearchIssues(t *testing.T) {
 						"q":               "is:issue field.priority:P1",
 						"page":            "1",
 						"per_page":        "30",
+						"search_type":     "semantic",
 						"advanced_search": "true",
 					},
 				).andThen(
@@ -1073,14 +1082,15 @@ func Test_SearchIssues(t *testing.T) {
 			expectedResult: mockSearchResult,
 		},
 		{
-			name: "query without field. qualifier does not set advanced_search",
+			name: "semantic search sets search_type",
 			mockedClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
 				GetSearchIssues: expectQueryParams(
 					t,
 					map[string]string{
-						"q":        "is:issue is:open",
-						"page":     "1",
-						"per_page": "30",
+						"q":           "is:issue is:open",
+						"page":        "1",
+						"per_page":    "30",
+						"search_type": "semantic",
 					},
 				).andThen(
 					mockResponse(t, http.StatusOK, mockSearchResult),

pkg/github/search_semantic_test.go

@@ -0,0 +1,87 @@
+package github
+
+import (
+	"testing"
+
+	"github.com/github/github-mcp-server/pkg/translations"
+	"github.com/github/github-mcp-server/pkg/utils"
+	"github.com/google/jsonschema-go/jsonschema"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_stripFreeTextQuotes(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		query    string
+		expected string
+	}{
+		{
+			name:     "leaves an unquoted query alone",
+			query:    "is:issue sticky sidebar",
+			expected: "is:issue sticky sidebar",
+		},
+		{
+			name:     "strips quotes around free text",
+			query:    `is:issue "sticky sidebar"`,
+			expected: "is:issue sticky sidebar",
+		},
+		{
+			name:     "preserves quotes around a multi-word qualifier value",
+			query:    `is:issue label:"needs triage"`,
+			expected: `is:issue label:"needs triage"`,
+		},
+		{
+			name:     "strips free text but preserves the qualifier alongside it",
+			query:    `is:issue label:"needs triage" "sticky sidebar"`,
+			expected: `is:issue label:"needs triage" sticky sidebar`,
+		},
+		{
+			name:     "preserves quotes on a hyphenated qualifier",
+			query:    `is:issue state-reason:"not planned"`,
+			expected: `is:issue state-reason:"not planned"`,
+		},
+		{
+			name:     "preserves quotes on a dotted custom field qualifier",
+			query:    `is:issue field.priority:"P1 urgent"`,
+			expected: `is:issue field.priority:"P1 urgent"`,
+		},
+		{
+			name:     "preserves quotes on a negated qualifier",
+			query:    `is:issue -label:"wont fix"`,
+			expected: `is:issue -label:"wont fix"`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, tt.expected, stripFreeTextQuotes(tt.query))
+		})
+	}
+}
+
+func Test_searchIssuesTool_descriptionMatchesEngine(t *testing.T) {
+	t.Parallel()
+
+	// The description has to describe the engine the host will actually use.
+	// Steering a lexical-only host toward paraphrased natural language is actively misleading.
+	semantic := SearchIssues(translations.NullTranslationHelper, WithHost(utils.HostTypeDotcom))
+	lexical := SearchIssues(translations.NullTranslationHelper, WithHost(utils.HostTypeGHES))
+
+	require.Equal(t, "search_issues", semantic.Tool.Name)
+	require.Equal(t, "search_issues", lexical.Tool.Name)
+
+	assert.Equal(t, searchIssuesSemanticDescription, semantic.Tool.Description)
+	assert.Equal(t, searchIssuesLexicalDescription, lexical.Tool.Description)
+
+	semanticSchema, ok := semantic.Tool.InputSchema.(*jsonschema.Schema)
+	require.True(t, ok)
+	lexicalSchema, ok := lexical.Tool.InputSchema.(*jsonschema.Schema)
+	require.True(t, ok)
+
+	assert.Equal(t, searchIssuesSemanticQueryDescription, semanticSchema.Properties["query"].Description)
+	assert.Equal(t, searchIssuesLexicalQueryDescription, lexicalSchema.Properties["query"].Description)
+}