openclaw - ✅(Solved) Fix write tool rejects empty/whitespace-only content as "missing required parameter" [1 pull requests, 2 comments, 3 participants]

openclaw2026-04-18 16:18:49

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openclaw/openclaw#68636•Fetched 2026-04-19 15:09:12

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commented ×2cross-referenced ×1

The write tool's parameter validator rejects content: "" and any whitespace-only value ("\n", " ", "\t") with the error "Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying."

This treats a legitimate operation (writing an empty or whitespace-only file — e.g. initializing an empty JSONL append-log, creating a sentinel file, or truncating an existing file) as a missing-parameter error. Because the error text tells the model to "Supply correct parameters before retrying", the model retries with another empty-ish value, gets the same error, and the turn ends with a user-visible "Write failed" banner without the file ever being created.

Error Message

write(path: "/tmp/empty.jsonl", content: "") → Error: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying.

write(path: "/tmp/empty.jsonl", content: "\n") → Error: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying.

Root Cause

In src/agents/pi-tools.params.ts:

export const REQUIRED_PARAM_GROUPS = {
  write: [
    { keys: ["path"], label: "path" },
    { keys: ["content"], label: "content" },  // no allowEmpty
  ],
  ...
};

assertRequiredParams checks value.trim().length > 0 unless the group has allowEmpty: true. The intent of that check is to catch a missing content param, but it also catches legitimate empty/whitespace-only content.

Fix Action

Fixed

Fixed by PR: fix(pi-tools): allow empty/whitespace-only content in write tool (https://github.com/openclaw/openclaw/pull/68637)

PR fix notes

PR #68637: fix(pi-tools): allow empty/whitespace-only content in write tool

Repository: openclaw/openclaw
Author: frankhli843
State: open | merged: False
Link: https://github.com/openclaw/openclaw/pull/68637

Description (problem / solution / changelog)

Closes #68636

Summary

The write tool's parameter validator currently rejects content: "" and any whitespace-only value with the error "Missing required parameter: content (received: path, content=<empty-string>)". This treats a legitimate operation (initializing an empty JSONL append-log, creating a sentinel file, or truncating an existing file) as a missing-parameter error, and because the error hints "Supply correct parameters before retrying" the model retries with the same or another empty value, gets the same error, and the turn ends with a user-visible Write failed banner without the file ever being created.

See the linked issue for a live reproduction with three model-driven retries in 39s.

Fix

Single change in src/agents/pi-tools.params.ts: add allowEmpty: true to the content group of REQUIRED_PARAM_GROUPS.write.

   write: [
     { keys: ["path"], label: "path" },
-    { keys: ["content"], label: "content" },
+    { keys: ["content"], label: "content", allowEmpty: true },
   ],

This is a one-flag change that uses the existing allowEmpty mechanism. The validator still rejects:

content key entirely missing
content as null or undefined
content as a non-string type (object, array)
path missing

It now accepts:

content: "" (empty write)
content: "\n" (newline-only, e.g. JSONL append-log initialization)
content: " \t\n " (all-whitespace)

Tests

Added a dedicated describe("REQUIRED_PARAM_GROUPS.write") block in src/agents/pi-tools.params.test.ts with six cases: three accepting (empty, newline, all-whitespace), three still-rejecting (missing content, non-string content, missing path). All pass locally.

Rationale

The intent of the .trim().length > 0 check is to catch content being missing (the model forgot the parameter), but it also catches the legitimate case where the model is intentionally writing an empty file. The existing allowEmpty flag exists for exactly this distinction. The write tool's natural semantics (create/truncate) should accept empty content.

Changed files

src/agents/pi-tools.params.test.ts (modified, +73/-0)
src/agents/pi-tools.params.ts (modified, +7/-1)

Code Example

write(path: "/tmp/empty.jsonl", content: "")
  → Error: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying.

write(path: "/tmp/empty.jsonl", content: "\n")
  → Error: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying.

---

11:55:08 [tools] write failed: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying. raw_params={"path":"/home/frank/.openclaw/workspace/knowledge/career/frank/interview-prep-progress.jsonl","content":""}
11:55:24 [tools] write failed: ... raw_params={"...","content":""}
11:55:47 [tools] write failed: ... raw_params={"...","content":"\n"}
11:59:50 ⚠️ ✍️ Write: `to ~/.openclaw/workspace/knowledge/career/frank/interview-prep-progress.jsonl (1 chars)` failed

---

export const REQUIRED_PARAM_GROUPS = {
  write: [
    { keys: ["path"], label: "path" },
    { keys: ["content"], label: "content" },  // no allowEmpty
  ],
  ...
};

---

{ keys: ["content"], label: "content", allowEmpty: true }

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Summary

Reproduce

write(path: "/tmp/empty.jsonl", content: "")
  → Error: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying.

write(path: "/tmp/empty.jsonl", content: "\n")
  → Error: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying.

Observed live (2026-04-18, three LLM-driven retries over 39 seconds, all with the same error, ending with a failed turn):

11:55:08 [tools] write failed: Missing required parameter: content (received: path, content=<empty-string>). Supply correct parameters before retrying. raw_params={"path":"/home/frank/.openclaw/workspace/knowledge/career/frank/interview-prep-progress.jsonl","content":""}
11:55:24 [tools] write failed: ... raw_params={"...","content":""}
11:55:47 [tools] write failed: ... raw_params={"...","content":"\n"}
11:59:50 ⚠️ ✍️ Write: `to ~/.openclaw/workspace/knowledge/career/frank/interview-prep-progress.jsonl (1 chars)` failed

Root cause

In src/agents/pi-tools.params.ts:

export const REQUIRED_PARAM_GROUPS = {
  write: [
    { keys: ["path"], label: "path" },
    { keys: ["content"], label: "content" },  // no allowEmpty
  ],
  ...
};

Fix (see linked PR)

Add allowEmpty: true to the content group:

{ keys: ["content"], label: "content", allowEmpty: true }

This accepts "", "\n", " " as valid. A completely missing content key, a null, or a non-string value still throws (covered by tests). The same pattern is already used elsewhere; this just applies it to the write tool where empty/truncate semantics are expected.

extent analysis

TL;DR

The issue can be fixed by adding allowEmpty: true to the content parameter group in src/agents/pi-tools.params.ts to allow empty or whitespace-only values.

Guidance

Review the REQUIRED_PARAM_GROUPS configuration in src/agents/pi-tools.params.ts to ensure that the allowEmpty property is set correctly for the content parameter.
Update the content group to include allowEmpty: true to permit empty or whitespace-only values.
Verify that the assertRequiredParams function is correctly handling the updated configuration.
Test the write tool with various input values, including empty strings and whitespace-only strings, to ensure that it behaves as expected.

Example

export const REQUIRED_PARAM_GROUPS = {
  write: [
    { keys: ["path"], label: "path" },
    { keys: ["content"], label: "content", allowEmpty: true },
  ],
  ...
};

Notes

This fix assumes that the intent is to allow empty or whitespace-only values for the content parameter, while still rejecting completely missing or invalid values.

Recommendation

Apply the workaround by adding allowEmpty: true to the content parameter group, as this will correctly handle empty or whitespace-only values while maintaining the existing validation logic.

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openclaw - ✅(Solved) Fix write tool rejects empty/whitespace-only content as "missing required parameter" [1 pull requests, 2 comments, 3 participants]

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Root Cause

Fix Action

Fixed

PR fix notes

PR #68637: fix(pi-tools): allow empty/whitespace-only content in write tool

Description (problem / solution / changelog)

Summary

Fix

Tests

Rationale

Changed files

Code Example

Summary

Reproduce

Root cause

Fix (see linked PR)

extent analysis

TL;DR

Guidance

Example

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openclaw - ✅(Solved) Fix write tool rejects empty/whitespace-only content as "missing required parameter" [1 pull requests, 2 comments, 3 participants]

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GitHub issue graph ai analysis

Error Message

Root Cause

Fix Action

Fixed

PR fix notes

PR #68637: fix(pi-tools): allow empty/whitespace-only content in write tool

Description (problem / solution / changelog)

Summary

Fix

Tests

Rationale

Changed files

Code Example

Summary

Reproduce

Root cause

Fix (see linked PR)

extent analysis

TL;DR

Guidance

Example

Notes

Recommendation

Still need to ship something?

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