feat(core): allow disabling tool output truncation

packages/opencode/src/config/config.ts

@@ -253,17 +253,20 @@ export const Info = Schema.Struct({
     }),
   ),
   tool_output: Schema.optional(
-    Schema.Struct({
+    Schema.Union([
-      max_lines: Schema.optional(PositiveInt).annotate({
+      Schema.Literal(false),
-        description: "Maximum lines of tool output before it is truncated and saved to disk (default: 2000)",
+      Schema.Struct({
+        max_lines: Schema.optional(PositiveInt).annotate({
+          description: "Maximum lines of tool output before it is truncated and saved to disk (default: 2000)",
+        }),
+        max_bytes: Schema.optional(PositiveInt).annotate({
+          description: "Maximum bytes of tool output before it is truncated and saved to disk (default: 51200)",
+        }),
       }),
-      max_bytes: Schema.optional(PositiveInt).annotate({
+    ]),
-        description: "Maximum bytes of tool output before it is truncated and saved to disk (default: 51200)",
-      }),
-    }),
   ).annotate({
     description:
-      "Thresholds for truncating tool output. When output exceeds either limit, the full text is written to the truncation directory and a preview is returned.",
+      "Configure tool output truncation, or set to false to disable it. When output exceeds either limit, the full text is written to the truncation directory and a preview is returned.",
   }),
   compaction: Schema.optional(
     Schema.Struct({

packages/opencode/src/skill/prompt/customize-opencode.md

@@ -126,7 +126,7 @@ Every field is optional.
     "mcp_timeout": 30000
   },
 
-  "tool_output": { "max_lines": 200, "max_bytes": 8192 },
+  "tool_output": false | { "max_lines": 200, "max_bytes": 8192 },
 
   "compaction": { "auto": true, "tail_turns": 15 }
 }
@@ -140,6 +140,7 @@ Shape notes worth being explicit about:
 - `plugin` is an array of strings or `[name, options]` tuples, not an object.
 - `mcp[name].command` is an array of strings, never a single string. `type` is required.
 - `permission` is either a string action or an object keyed by tool name.
+- `tool_output: false` disables shared tool output truncation; use an object to override its line and byte thresholds.
 
 ## Skills
 

packages/opencode/src/tool/shell.ts

@@ -433,7 +433,7 @@ export const ShellTool = Tool.define(
       ctx: Tool.Context,
     ) {
       const limits = yield* trunc.limits()
-      const keep = limits.maxBytes * 2
+      const keep = limits.enabled ? limits.maxBytes * 2 : Number.POSITIVE_INFINITY
       let full = ""
       let last = ""
       const list: Chunk[] = []
@@ -499,7 +499,7 @@ export const ShellTool = Tool.define(
                 sink?.write(chunk)
               } else {
                 full += chunk
-                if (Buffer.byteLength(full, "utf-8") > limits.maxBytes) {
+                if (limits.enabled && Buffer.byteLength(full, "utf-8") > limits.maxBytes) {
                   return trunc.write(full).pipe(
                     Effect.andThen((next) =>
                       Effect.sync(() => {
@@ -566,7 +566,7 @@ export const ShellTool = Tool.define(
       }
       if (aborted) meta.push("User aborted the command")
       const raw = list.map((item) => item.text).join("")
-      const end = tail(raw, limits.maxLines, limits.maxBytes)
+      const end = limits.enabled ? tail(raw, limits.maxLines, limits.maxBytes) : { text: raw, cut: false }
       if (end.cut) cut = true
       if (!file && end.cut) {
         file = yield* trunc.write(raw)

packages/opencode/src/tool/shell/prompt.ts

@@ -15,6 +15,7 @@ const descriptions = {
 }
 
 export type Limits = {
+  enabled: boolean
   maxLines: number
   maxBytes: number
 }
@@ -83,6 +84,11 @@ function chainGuidance(name: string) {
   return "If the commands depend on each other and must run sequentially, use a single Bash call with '&&' to chain them together (e.g., `git add . && git commit -m \"message\" && git push`). For instance, if one operation must complete before another starts (like mkdir before cp, Write before Bash for git operations, or git add before git commit), run these operations sequentially instead."
 }
 
+function truncationGuidance(limits: Limits, commands: string) {
+  if (!limits.enabled) return ""
+  return `\n  - If the output exceeds ${limits.maxLines} lines or ${limits.maxBytes} bytes, it will be truncated and the full output will be written to a file. You can use Read with offset/limit to read specific sections or Grep to search the full content. Do NOT use ${commands} to limit output; the full output will already be captured to a file for more precise searching.`
+}
+
 function bashCommandSection(chain: string, limits: Limits) {
   return `Before executing the command, please follow these steps:
 
@@ -103,8 +109,7 @@ function bashCommandSection(chain: string, limits: Limits) {
 Usage notes:
   - The command argument is required.
   - You can specify an optional timeout in milliseconds. If not specified, commands will time out after 120000ms (2 minutes).
-  - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.
+  - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.${truncationGuidance(limits, "`head`, `tail`, or other truncation commands")}
-  - If the output exceeds ${limits.maxLines} lines or ${limits.maxBytes} bytes, it will be truncated and the full output will be written to a file. You can use Read with offset/limit to read specific sections or Grep to search the full content. Do NOT use \`head\`, \`tail\`, or other truncation commands to limit output; the full output will already be captured to a file for more precise searching.
 
   - Avoid using Bash with the \`find\`, \`grep\`, \`cat\`, \`head\`, \`tail\`, \`sed\`, \`awk\`, or \`echo\` commands, unless explicitly instructed or when these commands are truly necessary for the task. Instead, always prefer using the dedicated tools for these commands:
     - File search: Use Glob (NOT find or ls)
@@ -149,8 +154,7 @@ Before executing the command, please follow these steps:
 Usage notes:
   - The command argument is required.
   - You can specify an optional timeout in milliseconds. If not specified, commands will time out after 120000ms (2 minutes).
-  - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.
+  - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.${truncationGuidance(limits, "`Select-Object -First`, `Select-Object -Last`, or other truncation commands")}
-  - If the output exceeds ${limits.maxLines} lines or ${limits.maxBytes} bytes, it will be truncated and the full output will be written to a file. You can use Read with offset/limit to read specific sections or Grep to search the full content. Do NOT use \`Select-Object -First\`, \`Select-Object -Last\`, or other truncation commands to limit output; the full output will already be captured to a file for more precise searching.
 
   - Avoid using Shell with PowerShell file/content cmdlets unless explicitly instructed or when these cmdlets are truly necessary for the task. Instead, always prefer using the dedicated tools for these commands:
     - File search: Use Glob (NOT Get-ChildItem)
@@ -199,8 +203,7 @@ Before executing the command, please follow these steps:
 Usage notes:
   - The command argument is required.
   - You can specify an optional timeout in milliseconds. If not specified, commands will time out after 120000ms (2 minutes).
-  - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.
+  - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.${truncationGuidance(limits, "`more` or other pagination commands")}
-  - If the output exceeds ${limits.maxLines} lines or ${limits.maxBytes} bytes, it will be truncated and the full output will be written to a file. You can use Read with offset/limit to read specific sections or Grep to search the full content. Do NOT use \`more\` or other pagination commands to limit output; the full output will already be captured to a file for more precise searching.
 
   - Avoid using Shell with cmd.exe file/content commands unless explicitly instructed or when these commands are truly necessary for the task. Instead, always prefer using the dedicated tools for these commands:
     - File search: Use Glob (NOT dir /s)

packages/opencode/src/tool/truncate.ts

@@ -19,6 +19,7 @@ export const DIR = TRUNCATION_DIR
 export const GLOB = path.join(TRUNCATION_DIR, "*")
 
 export type Result = { content: string; truncated: false } | { content: string; truncated: true; outputPath: string }
+export type Limits = { enabled: boolean; maxLines: number; maxBytes: number }
 
 export interface Options {
   maxLines?: number
@@ -40,9 +41,9 @@ export interface Interface {
    */
   readonly output: (text: string, options?: Options, agent?: Agent.Info) => Effect.Effect<Result>
   /**
-   * Resolved truncation limits: values from `tool_output` in opencode config, or MAX_LINES / MAX_BYTES if unset.
+   * Resolved truncation state and limits from `tool_output` in opencode config.
    */
-  readonly limits: () => Effect.Effect<{ maxLines: number; maxBytes: number }>
+  readonly limits: () => Effect.Effect<Limits>
 }
 
 export class Service extends Context.Service<Service, Interface>()("@opencode/Truncate") {}
@@ -75,9 +76,11 @@ export const layer = Layer.effect(
 
     const limits = Effect.fn("Truncate.limits")(function* () {
       const configSvc = yield* Effect.serviceOption(Config.Service)
-      if (Option.isNone(configSvc)) return { maxLines: MAX_LINES, maxBytes: MAX_BYTES }
+      if (Option.isNone(configSvc)) return { enabled: true, maxLines: MAX_LINES, maxBytes: MAX_BYTES }
       const cfg = yield* configSvc.value.get().pipe(Effect.catch(() => Effect.succeed(undefined)))
+      if (cfg?.tool_output === false) return { enabled: false, maxLines: MAX_LINES, maxBytes: MAX_BYTES }
       return {
+        enabled: true,
         maxLines: cfg?.tool_output?.max_lines ?? MAX_LINES,
         maxBytes: cfg?.tool_output?.max_bytes ?? MAX_BYTES,
       }
@@ -85,6 +88,7 @@ export const layer = Layer.effect(
 
     const output = Effect.fn("Truncate.output")(function* (text: string, options: Options = {}, agent?: Agent.Info) {
       const resolved = yield* limits()
+      if (!resolved.enabled) return { content: text, truncated: false } as const
       const maxLines = options.maxLines ?? resolved.maxLines
       const maxBytes = options.maxBytes ?? resolved.maxBytes
       const direction = options.direction ?? "head"

packages/opencode/test/tool/shell.test.ts

@@ -1200,6 +1200,29 @@ describe("tool.shell truncation", () => {
     ),
   )
 
+  it.live("does not truncate output when tool_output is disabled", () =>
+    Effect.gen(function* () {
+      const tmp = yield* tmpdirScoped({ config: { tool_output: false } })
+      yield* runIn(
+        tmp,
+        Effect.gen(function* () {
+          const bash = yield* initShell()
+          expect(bash.description).not.toContain("If the output exceeds")
+          const result = yield* bash.execute(
+            {
+              command: fill("bytes", Truncate.MAX_BYTES + 10000),
+              description: "Generate bytes with truncation disabled",
+            },
+            ctx,
+          )
+          expect(result.metadata.truncated).toBe(false)
+          expect(result.output).not.toContain("...output truncated...")
+          expect(Buffer.byteLength(result.output, "utf-8")).toBeGreaterThan(Truncate.MAX_BYTES)
+        }),
+      )
+    }),
+  )
+
   it.live("full output is saved to file when truncated", () =>
     runIn(
       projectRoot,

packages/opencode/test/tool/truncation.test.ts

@@ -110,6 +110,7 @@ describe("Truncate", () => {
       Effect.gen(function* () {
         const svc = yield* Truncate.Service
         const resolved = yield* svc.limits()
+        expect(resolved.enabled).toBe(true)
         expect(resolved.maxLines).toBe(Truncate.MAX_LINES)
         expect(resolved.maxBytes).toBe(Truncate.MAX_BYTES)
       }),
@@ -120,6 +121,7 @@ describe("Truncate", () => {
       limitsIt.live("limits() reflects config overrides", () =>
         Effect.gen(function* () {
           const resolved = yield* (yield* Truncate.Service).limits()
+          expect(resolved.enabled).toBe(true)
           expect(resolved.maxLines).toBe(123)
           expect(resolved.maxBytes).toBe(456)
         }),
@@ -159,6 +161,18 @@ describe("Truncate", () => {
           expect(result.truncated).toBe(false)
         }),
       )
+
+      const disabledIt = configuredIt({ tool_output: false })
+      disabledIt.live("does not truncate output when disabled", () =>
+        Effect.gen(function* () {
+          const content = "a".repeat(Truncate.MAX_BYTES + 1)
+          const svc = yield* Truncate.Service
+          const resolved = yield* svc.limits()
+          const result = yield* svc.output(content)
+          expect(resolved.enabled).toBe(false)
+          expect(result).toEqual({ content, truncated: false })
+        }),
+      )
     })
 
     it.live("large single-line file truncates with byte message", () =>

packages/sdk/js/src/v2/gen/types.gen.ts

@@ -1294,10 +1294,15 @@ export type Config = {
   enterprise?: {
     url?: string
   }
-  tool_output?: {
+  /**
-    max_lines?: number
+   * Configure tool output truncation, or set to false to disable it. When output exceeds either limit, the full text is written to the truncation directory and a preview is returned.
-    max_bytes?: number
+   */
-  }
+  tool_output?:
+    | false
+    | {
+        max_lines?: number
+        max_bytes?: number
+      }
   compaction?: {
     auto?: boolean
     prune?: boolean

packages/web/src/content/docs/config.mdx

@@ -372,6 +372,15 @@ You can control when tool output is truncated using the `tool_output` option. Wh
 
 These thresholds apply to output handled by OpenCode's shared truncation layer, including MCP and plugin tool output. Individual tools that page or cap their own results can have separate limits.
 
+To disable shared tool output truncation, set `tool_output` to `false`:
+
+```json title="opencode.json"
+{
+  "$schema": "https://opencode.ai/config.json",
+  "tool_output": false
+}
+```
+
 ---
 
 ### Models