diff --git a/packages/core/src/codemode/tool.ts b/packages/core/src/codemode/tool.ts
index 224d097a2af..9808b2ed4c5 100644
--- a/packages/core/src/codemode/tool.ts
+++ b/packages/core/src/codemode/tool.ts
@@ -1,7 +1,15 @@
 export * as CodeModeTool from "./tool.js"
 
-import { CodeMode, Tool, toolError } from "@opencode-ai/codemode"
-import type { Content, Context, Error, Info, Metadata, Result } from "@opencode-ai/schema/tool"
+import { CodeMode, Namespace, Tool, toolError } from "@opencode-ai/codemode"
+import type {
+  Content,
+  Context,
+  Error,
+  Info,
+  Metadata,
+  Namespace as ToolNamespace,
+  Result,
+} from "@opencode-ai/schema/tool"
 import { Effect, Ref, Schema, Semaphore } from "effect"
 import { definition, normalizedName } from "../tool/runtime.js"
 
@@ -44,6 +52,7 @@ const description = [
 export const create = (
   registrations: ReadonlyMap<string, Info>,
   executeTool: (name: string, tool: Info, input: unknown, context: Context) => Effect.Effect<Result, Error>,
+  namespaces: ReadonlyMap<string, ToolNamespace> = new Map(),
 ) => {
   return {
     name: "execute",
@@ -62,6 +71,7 @@ export const create = (
           )
         const result = yield* runtime(
           registrations,
+          namespaces,
           (name, tool, input) =>
             Effect.gen(function* () {
               const index = yield* Ref.getAndUpdate(callIndex, (index) => index + 1)
@@ -132,23 +142,27 @@ export const create = (
   } satisfies Info
 }
 
-export const catalog = (registrations: ReadonlyMap<string, Info>) => {
+export const catalog = (
+  registrations: ReadonlyMap<string, Info>,
+  namespaces: ReadonlyMap<string, ToolNamespace> = new Map(),
+) => {
   const pinned = new Set(
     Array.from(registrations.values())
       .filter((registration) => registration.options?.pinned === true)
       .map(qualifiedName),
   )
-  return runtime(registrations, () => Effect.fail(toolError("Execute context is unavailable")))
+  return runtime(registrations, namespaces, () => Effect.fail(toolError("Execute context is unavailable")))
     .catalog()
     .map((entry) => ({ ...entry, pinned: pinned.has(entry.path) }))
 }
 
 function runtime(
   registrations: ReadonlyMap<string, Info>,
+  namespaces: ReadonlyMap<string, ToolNamespace>,
   executeTool: (name: string, tool: Info, input: unknown) => Effect.Effect<unknown, unknown>,
   hooks?: CodeMode.ToolCallHooks,
 ) {
-  const tools: Record<string, Tool.Tool<never>> = {}
+  const tools: Record<string, Tool.Tool<never> | Namespace.Namespace<never>> = {}
   for (const [name, registration] of registrations) {
     const child = definition(registration)
     const path = qualifiedName(registration)
@@ -159,6 +173,9 @@ function runtime(
       execute: (input) => executeTool(name, registration, input),
     })
   }
+  for (const namespace of namespaces.values())
+    if (!Object.hasOwn(tools, namespace.name))
+      tools[namespace.name] = Namespace.make({ description: namespace.description, tools: {} })
   return CodeMode.make<typeof tools>({ tools, ...hooks })
 }
 
diff --git a/packages/core/src/tool.ts b/packages/core/src/tool.ts
index d1dc8c581fd..84084f1fbcd 100644
--- a/packages/core/src/tool.ts
+++ b/packages/core/src/tool.ts
@@ -1,6 +1,6 @@
 export * as Tool from "./tool.js"
 export { CallID, Content, Error, FileContent, TextContent } from "@opencode-ai/schema/tool"
-export type { Context, Metadata, Options, Result } from "@opencode-ai/schema/tool"
+export type { Context, Metadata, Namespace, Options, Result } from "@opencode-ai/schema/tool"
 
 import { ToolDefinition, type ToolCall } from "@opencode-ai/ai"
 import { Tool } from "@opencode-ai/schema/tool"
@@ -26,6 +26,7 @@ export class RegistrationError extends Schema.TaggedError<RegistrationError>()("
 export interface Draft {
   readonly list: () => readonly (Tool.Info & { readonly id: string })[]
   readonly get: (id: string) => (Tool.Info & { readonly id: string }) | undefined
+  readonly namespace: (namespace: Tool.Namespace) => void
   readonly add: (tool: Tool.Info) => void
   readonly update: (id: string, update: (tool: Types.Mutable<Tool.Info>) => void) => void
   readonly remove: (id: string) => void
@@ -33,7 +34,8 @@ export interface Draft {
 
 type Data = {
   tools: Map<string, Tool.Info & { readonly id: string }>
-  errors: { tool: Tool.Info; error: RegistrationError }[]
+  namespaces: Map<string, Tool.Namespace>
+  errors: { kind: "tool" | "namespace"; name: string; namespace?: string; error: RegistrationError }[]
 }
 
 export interface Interface extends State.Transformable<Draft> {
@@ -151,15 +153,24 @@ const layer = Layer.effect(
       name: "tool",
       initial: () => ({
         tools: new Map(),
+        namespaces: new Map(),
         errors: [],
       }),
       draft: (draft) => ({
         list: () => Array.from(draft.tools.values()),
         get: (id) => draft.tools.get(id),
+        namespace: (namespace) => {
+          const error = namespaceError(namespace.name)
+          if (error) {
+            draft.errors.push({ kind: "namespace", name: namespace.name, namespace: namespace.name, error })
+            return
+          }
+          draft.namespaces.set(namespace.name, { ...namespace })
+        },
         add: (tool) => {
           const error = registrationError(tool)
           if (error) {
-            draft.errors.push({ tool, error })
+            draft.errors.push({ kind: "tool", name: tool.name, namespace: tool.options?.namespace, error })
             return
           }
           const id = effectiveName(tool)
@@ -176,7 +187,7 @@ const layer = Layer.effect(
             tool.options = { ...tool.options, namespace: current.options?.namespace }
           const error = registrationError(tool)
           if (error) {
-            draft.errors.push({ tool, error })
+            draft.errors.push({ kind: "tool", name: tool.name, namespace: tool.options?.namespace, error })
             return
           }
           draft.tools.set(id, tool)
@@ -188,10 +199,10 @@ const layer = Layer.effect(
       finalize: () =>
         Effect.forEach(
           state.get().errors,
-          ({ tool, error }) =>
-            Effect.logError("Skipping invalid tool registration", {
-              name: tool.name,
-              namespace: tool.options?.namespace,
+          ({ kind, name, namespace, error }) =>
+            Effect.logError(`Skipping invalid ${kind} registration`, {
+              name,
+              namespace,
               error: error.message,
             }),
           { discard: true },
@@ -213,13 +224,16 @@ const layer = Layer.effect(
           const codemode = new Map(Array.from(active).filter(([, tool]) => tool.options?.codemode !== false))
           const codemodeEnabled = !whollyDisabled("execute", rules)
           const codemodeTool = codemodeEnabled
-            ? CodeModeTool.create(codemode, (name, tool, input, context) =>
-                beforeExecute(name, input, context).pipe(
-                  Effect.flatMap((event) => executeTool(tool, name, event.input, context)),
-                ),
+            ? CodeModeTool.create(
+                codemode,
+                (name, tool, input, context) =>
+                  beforeExecute(name, input, context).pipe(
+                    Effect.flatMap((event) => executeTool(tool, name, event.input, context)),
+                  ),
+                state.get().namespaces,
               )
             : undefined
-          const codeModeCatalog = codemodeEnabled ? CodeModeTool.catalog(codemode) : undefined
+          const codeModeCatalog = codemodeEnabled ? CodeModeTool.catalog(codemode, state.get().namespaces) : undefined
           return {
             ...(codeModeCatalog === undefined ? {} : { codeModeCatalog }),
             definitions: [
@@ -269,8 +283,10 @@ function schemaMakeError(error: unknown) {
 
 function registrationError(tool: Tool.Info) {
   const namespace = tool.options?.namespace
-  if (namespace !== undefined && !namespace.split(".").every((segment) => /^[A-Za-z0-9_-]{1,64}$/.test(segment)))
-    return new RegistrationError({ name: namespace, message: `Invalid tool namespace: ${JSON.stringify(namespace)}` })
+  if (namespace !== undefined) {
+    const error = namespaceError(namespace)
+    if (error) return error
+  }
   const name = normalizedName(tool)
   if (!/^[A-Za-z0-9_-]{1,64}$/.test(name)) return new RegistrationError({ name, message: `Invalid tool name: ${name}` })
   const id = effectiveName(tool)
@@ -284,6 +300,11 @@ function registrationError(tool: Tool.Info) {
   return Result.isFailure(result) ? result.failure : undefined
 }
 
+function namespaceError(name: string) {
+  if (name.split(".").every((segment) => /^[A-Za-z0-9_-]{1,64}$/.test(segment))) return
+  return new RegistrationError({ name, message: `Invalid tool namespace: ${JSON.stringify(name)}` })
+}
+
 export const node = makeLocationNode({
   service: Service,
   layer,
diff --git a/packages/core/src/tool/AGENTS.md b/packages/core/src/tool/AGENTS.md
index d307b95efc8..5b26235e0a4 100644
--- a/packages/core/src/tool/AGENTS.md
+++ b/packages/core/src/tool/AGENTS.md
@@ -32,6 +32,8 @@ Leaves own resolution, permission, and side-effect ordering. Translate only expe
 
 Built-ins, plugins, and MCP install tools through `Tool.Service.transform`, adding complete tool objects to the draft. A tool may provide a namespace, which flattens direct model names to `<namespace>_<tool>`, and defaults into CodeMode (`codemode` defaults true; `codemode: false` keeps the tool on the provider's native tool list).
 
+Namespace descriptions are registered once through `draft.namespace(...)`. Tool options continue to reference the namespace by string name; an unregistered namespace remains valid and simply has no namespace description.
+
 The service uses shared `State` to replay synchronous transforms in registration order against a fresh draft. `Tool.Service.reload()` rebuilds from captured source data without changing registration precedence. Registrations are scoped and return a real, idempotent `dispose` Effect:
 
 - The latest valid active registration for the same effective name wins.
diff --git a/packages/core/test/tool-registry.test.ts b/packages/core/test/tool-registry.test.ts
index b38826585c1..1a965e73858 100644
--- a/packages/core/test/tool-registry.test.ts
+++ b/packages/core/test/tool-registry.test.ts
@@ -534,6 +534,7 @@ describe("Tool", () => {
     Effect.gen(function* () {
       const service = yield* Tool.Service
       yield* service.transform((draft) => {
+        draft.namespace({ name: "invalid..namespace", description: "Invalid" })
         draft.add({ ...make(), name: "first", options: { codemode: false } })
         draft.add({ ...make(), name: "second", options: { namespace: "invalid..namespace", codemode: false } })
         draft.add({ ...make(), name: "second", options: { namespace: "invalid__namespace" } })
@@ -545,6 +546,32 @@ describe("Tool", () => {
     }),
   )
 
+  it.effect("registers namespace descriptions separately from namespaced tools", () =>
+    Effect.gen(function* () {
+      const service = yield* Tool.Service
+      yield* service.transform((draft) => {
+        draft.namespace({ name: "registry", description: "Package publishing and discovery" })
+        draft.add({ ...make(), name: "plain", options: { namespace: "legacy" } })
+        draft.add({ ...make(), name: "direct", options: { namespace: "registry", codemode: false } })
+        draft.add({ ...make(), name: "search", description: "Search packages", options: { namespace: "registry" } })
+      })
+
+      const snapshot = yield* service.snapshot()
+      expect(snapshot.definitions.map((tool) => tool.name)).toEqual(["registry_direct", "execute"])
+      expect(snapshot.codeModeCatalog?.map((tool) => tool.path)).toEqual(["legacy.plain", "registry.search"])
+      const result = yield* snapshot.execute({
+        ...call("execute"),
+        call: {
+          type: "tool-call",
+          id: "namespace-search",
+          name: "execute",
+          input: { code: 'return search({ query: "publishing discovery" })' },
+        },
+      })
+      expect(result.output).toMatchObject({ output: expect.stringContaining("tools.registry.search") })
+    }),
+  )
+
   it.effect("logs invalid tool definitions without dropping healthy tools", () => {
     const output: unknown[] = []
     const logger = Logger.map(Logger.formatStructured, (entry) => {
diff --git a/packages/plugin/src/effect/index.ts b/packages/plugin/src/effect/index.ts
index 2ac5a13e1e8..32987b2a5ac 100644
--- a/packages/plugin/src/effect/index.ts
+++ b/packages/plugin/src/effect/index.ts
@@ -14,5 +14,6 @@ export { Provider } from "@opencode-ai/schema/provider"
 export { Reference } from "@opencode-ai/schema/reference"
 export { Rpc } from "@opencode-ai/schema/rpc"
 export { Skill } from "@opencode-ai/schema/skill"
+export { Tool } from "@opencode-ai/schema/tool"
 export { Vcs } from "@opencode-ai/schema/vcs"
 export { WebSearch } from "@opencode-ai/schema/websearch"
diff --git a/packages/plugin/src/effect/tool.ts b/packages/plugin/src/effect/tool.ts
index 9f934ed6ccf..d448fed7389 100644
--- a/packages/plugin/src/effect/tool.ts
+++ b/packages/plugin/src/effect/tool.ts
@@ -8,6 +8,7 @@ import type { Hooks, Transform } from "./registration.js"
 export interface ToolDraft {
   list(): readonly (Tool.Info & { readonly id: string })[]
   get(id: string): (Tool.Info & { readonly id: string }) | undefined
+  namespace(namespace: Tool.Namespace): void
   add<Input extends Tool.ValueSchema<any>, Output extends Tool.ValueSchema<any> | undefined>(
     tool: Tool.Info<Input, Output>,
   ): void
diff --git a/packages/plugin/src/promise/adapter.ts b/packages/plugin/src/promise/adapter.ts
index 0eaa50270d9..346e121ddf0 100644
--- a/packages/plugin/src/promise/adapter.ts
+++ b/packages/plugin/src/promise/adapter.ts
@@ -465,6 +465,7 @@ export function fromPromise(plugin: Plugin) {
                       const tool = draft.get(id)
                       return tool ? { ...tool, execute: promiseExecutor(tool.execute) } : undefined
                     },
+                    namespace: draft.namespace,
                     add: (tool: Info) =>
                       draft.add({
                         ...tool,
diff --git a/packages/plugin/src/promise/index.ts b/packages/plugin/src/promise/index.ts
index 37dbf1e13be..f784d66e756 100644
--- a/packages/plugin/src/promise/index.ts
+++ b/packages/plugin/src/promise/index.ts
@@ -15,5 +15,6 @@ export { Provider } from "@opencode-ai/schema/provider"
 export { Reference } from "@opencode-ai/schema/reference"
 export { Rpc } from "@opencode-ai/schema/rpc"
 export { Skill } from "@opencode-ai/schema/skill"
+export { Tool } from "@opencode-ai/schema/tool"
 export { Vcs } from "@opencode-ai/schema/vcs"
 export { WebSearch } from "@opencode-ai/schema/websearch"
diff --git a/packages/plugin/src/promise/tool.ts b/packages/plugin/src/promise/tool.ts
index 0dbd9000568..12484a6708c 100644
--- a/packages/plugin/src/promise/tool.ts
+++ b/packages/plugin/src/promise/tool.ts
@@ -25,6 +25,7 @@ export type Info<
 interface ToolDraft {
   list(): readonly (Info & { readonly id: string })[]
   get(id: string): (Info & { readonly id: string }) | undefined
+  namespace(namespace: Tool.Namespace): void
   add<Input extends Tool.ValueSchema<any>, Output extends Tool.ValueSchema<any> | undefined>(
     tool: Info<Input, Output>,
   ): void
diff --git a/packages/plugin/test/contract-identity.test.ts b/packages/plugin/test/contract-identity.test.ts
index 1b232ab68a8..80ff2a6e39f 100644
--- a/packages/plugin/test/contract-identity.test.ts
+++ b/packages/plugin/test/contract-identity.test.ts
@@ -13,6 +13,7 @@ import { Provider } from "@opencode-ai/schema/provider"
 import { Reference } from "@opencode-ai/schema/reference"
 import { Rpc } from "@opencode-ai/schema/rpc"
 import { Skill } from "@opencode-ai/schema/skill"
+import { Tool } from "@opencode-ai/schema/tool"
 import { Vcs } from "@opencode-ai/schema/vcs"
 import { WebSearch } from "@opencode-ai/schema/websearch"
 
@@ -39,6 +40,7 @@ test.each([
   expect(entrypoint.Reference).toBe(Reference)
   expect(entrypoint.Rpc).toBe(Rpc)
   expect(entrypoint.Skill).toBe(Skill)
+  expect(entrypoint.Tool).toBe(Tool)
   expect(entrypoint.Vcs).toBe(Vcs)
   expect(entrypoint.WebSearch).toBe(WebSearch)
   expect(Object.keys(entrypoint).sort()).toEqual([
@@ -56,6 +58,7 @@ test.each([
     "Reference",
     "Rpc",
     "Skill",
+    "Tool",
     "Vcs",
     "WebSearch",
   ])
diff --git a/packages/schema/src/tool.ts b/packages/schema/src/tool.ts
index 7f87dccb9ba..06dec1c0c57 100644
--- a/packages/schema/src/tool.ts
+++ b/packages/schema/src/tool.ts
@@ -19,6 +19,11 @@ export interface Context {
   readonly progress: (update: Metadata) => Effect.Effect<void>
 }
 
+export interface Namespace {
+  readonly name: string
+  readonly description: string
+}
+
 interface BaseOptions {
   readonly namespace?: string
   readonly permission?: string
diff --git a/packages/www/src/docs/content/build/plugins/effect.mdx b/packages/www/src/docs/content/build/plugins/effect.mdx
index 6b902c3fafd..0315148f408 100644
--- a/packages/www/src/docs/content/build/plugins/effect.mdx
+++ b/packages/www/src/docs/content/build/plugins/effect.mdx
@@ -838,6 +838,10 @@ effect: (ctx) =>
   Effect.gen(function* () {
     const tool = ctx.tool
     yield* tool.transform((draft) => {
+      draft.namespace({
+        name: "acme",
+        description: "Customer account tools",
+      })
       draft.add({
         name: "greeting",
         description: "Create a greeting",
@@ -854,6 +858,9 @@ effect: (ctx) =>
   }),
 ```
 
+Register a namespace once to add model-visible search context for every CodeMode tool assigned to it. Tools continue
+to reference the namespace by its string name. Namespace registration is optional when no description is needed.
+
 Call `yield* ctx.tool.reload()` after changing source data captured by the callback. Reload replays active transforms
 without changing their order; it does not rerun the plugin effect.
 
@@ -889,6 +896,7 @@ Schemas: [`Tool.Content`](/api#schema-Tool.Content), [`Tool.TextContent`](/api#s
 interface ToolDraft {
   list(): readonly (Tool.Info & { readonly id: string })[]
   get(id: string): (Tool.Info & { readonly id: string }) | undefined
+  namespace(namespace: Tool.Namespace): void
   add<Input extends Tool.ValueSchema<any>, Output extends Tool.ValueSchema<any> | undefined>(
     tool: Tool.Info<Input, Output>,
   ): void
diff --git a/packages/www/src/docs/content/build/plugins/index.mdx b/packages/www/src/docs/content/build/plugins/index.mdx
index 7fbf7cce9c2..4e3def3b251 100644
--- a/packages/www/src/docs/content/build/plugins/index.mdx
+++ b/packages/www/src/docs/content/build/plugins/index.mdx
@@ -799,6 +799,10 @@ For the same effective tool name, a later valid registration overrides an earlie
 
 ```ts
 const registration = await ctx.tool.transform((draft) => {
+  draft.namespace({
+    name: "acme",
+    description: "Customer account tools",
+  })
   draft.add({
     name: "greeting",
     description: "Create a greeting",
@@ -817,6 +821,9 @@ const registration = await ctx.tool.transform((draft) => {
 })
 ```
 
+Register a namespace once to add model-visible search context for every CodeMode tool assigned to it. Tools continue
+to reference the namespace by its string name. Namespace registration is optional when no description is needed.
+
 Call `reload()` after changing source data captured by the callback. Reload replays the active transforms without
 changing their order; it does not rerun plugin setup.
 
@@ -868,6 +875,7 @@ interface ToolContext {
 interface ToolDraft {
   list(): readonly (ToolInfo & { readonly id: string })[]
   get(id: string): (ToolInfo & { readonly id: string }) | undefined
+  namespace(namespace: Tool.Namespace): void
   add(tool: ToolInfo): void
   update(id: string, update: (tool: Types.Mutable<ToolInfo>) => void): void
   remove(id: string): void