simplify: remove lazy toolsByName map - not needed for actual use cases

FindToolByName() is only called once per request at most (to find toolset ID
for dynamic enablement). The SDK handles tool dispatch after registration.

A simple linear scan over ~90 tools is trivially fast and avoids:
- sync.Once complexity
- Map allocation
- Premature optimization for non-existent 'repeated lookups'

The pre-computed maps we keep (toolsetIDSet, etc.) are justified because
they're used for filtering logic that runs on every request.

Author: SamMorrowDrums

pkg/registry/builder.go

@@ -125,8 +125,6 @@ func (b *Builder) Build() *Registry {
 		featureChecker:    b.featureChecker,
 	}
 
-	// Note: toolsByName map is lazy-initialized on first use via getToolsByName()
-
 	// Process toolsets and pre-compute metadata in a single pass
 	r.enabledToolsets, r.unrecognizedToolsets, r.toolsetIDs, r.toolsetIDSet, r.defaultToolsetIDs, r.toolsetDescriptions = b.processToolsets()
 

pkg/registry/registry.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"slices"
 	"sort"
-	"sync"
 
 	"github.com/modelcontextprotocol/go-sdk/mcp"
 )
@@ -28,10 +27,6 @@ import (
 type Registry struct {
 	// tools holds all tools in this group (ordered for iteration)
 	tools []ServerTool
-	// toolsByName provides O(1) lookup by tool name (lazy-initialized)
-	// Used by FindToolByName for repeated lookups in long-lived servers
-	toolsByName     map[string]*ServerTool
-	toolsByNameOnce sync.Once
 	// resourceTemplates holds all resource templates in this group (ordered for iteration)
 	resourceTemplates []ServerResourceTemplate
 	// prompts holds all prompts in this group (ordered for iteration)
@@ -68,18 +63,6 @@ func (r *Registry) UnrecognizedToolsets() []string {
 	return r.unrecognizedToolsets
 }
 
-// getToolsByName returns the toolsByName map, initializing it lazily on first call.
-// Used by FindToolByName for O(1) lookups in long-lived servers with repeated lookups.
-func (r *Registry) getToolsByName() map[string]*ServerTool {
-	r.toolsByNameOnce.Do(func() {
-		r.toolsByName = make(map[string]*ServerTool, len(r.tools))
-		for i := range r.tools {
-			r.toolsByName[r.tools[i].Tool.Name] = &r.tools[i]
-		}
-	})
-	return r.toolsByName
-}
-
 // MCP method constants for use with ForMCPRequest.
 const (
 	MCPMethodInitialize             = "initialize"
@@ -237,8 +220,10 @@ func (r *Registry) ResolveToolAliases(toolNames []string) (resolved []string, al
 // Returns the tool, its toolset ID, and an error if not found.
 // This searches ALL tools regardless of filters.
 func (r *Registry) FindToolByName(toolName string) (*ServerTool, ToolsetID, error) {
-	if tool, ok := r.getToolsByName()[toolName]; ok {
-		return tool, tool.Toolset.ID, nil
+	for i := range r.tools {
+		if r.tools[i].Tool.Name == toolName {
+			return &r.tools[i], r.tools[i].Toolset.ID, nil
+		}
 	}
 	return nil, "", NewToolDoesNotExistError(toolName)
 }