vercel/ai · error

maxInputBytesPerCall must be greater than 0

Error message

maxInputBytesPerCall must be greater than 0

What it means

Each skill must have a unique name, since the name becomes its directory under the skills root. validateACPSkills tracks names in a set and throws on the second occurrence. Duplicates would silently overwrite each other's files, so they are rejected up front.

Source

Thrown at packages/ai/src/embed/embed-many.ts:455

}

const textEncoder = new TextEncoder();

function splitByEmbeddingLimits({
  values,
  maxEmbeddingsPerCall,
  maxInputBytesPerCall,
}: {
  values: Array<string>;
  maxEmbeddingsPerCall: number;
  maxInputBytesPerCall: number;
}): Array<Array<string>> {
  if (maxEmbeddingsPerCall <= 0) {
    throw new Error('maxEmbeddingsPerCall must be greater than 0');
  }

  if (maxInputBytesPerCall <= 0) {
    throw new Error('maxInputBytesPerCall must be greater than 0');
  }

  if (values.length === 0) {
    return [];
  }

  const chunks: Array<Array<string>> = [];
  let currentChunk: Array<string> = [];
  let currentInputBytes = 0;

  for (const value of values) {
    const inputBytes = textEncoder.encode(value).length;

    if (
      currentChunk.length > 0 &&
      (currentChunk.length >= maxEmbeddingsPerCall ||
        currentInputBytes + inputBytes > maxInputBytesPerCall)
    ) {

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Deduplicate skills by name before passing them (keep the intended one, e.g. project over user-level).
2. Rename one of the conflicting skills to a distinct kebab-case slug.
3. Detect conflicts early by building a Set of names and asserting uniqueness in your loader.

Example fix

// before
[{ name: 'reviewer' }, { name: 'reviewer' }]

// after
[{ name: 'project-reviewer' }, { name: 'user-reviewer' }]

function dedupeSkills(skills: Array<{ name: string }> ) {
  const seen = new Set<string>();
  const out: typeof skills = [];
  for (const s of skills) {
    if (seen.has(s.name)) continue; // or rename
    seen.add(s.name);
    out.push(s);
  }
  return out;
}

try {
  await agent.addSkills(mergedSkills);
} catch (error) {
  if (error instanceof Error && error.message.startsWith('Duplicate ACP skill name')) {
    const dup = error.message.match(/"([^"]+)"/)?.[1];
    await agent.addSkills(dedupeSkills(mergedSkills).filter(s => s.name !== dup || keepPreferred(s)));
  } else {
    throw error;
  }
}

When it happens

Trigger: Passing an array of skills to the ACP harness where two entries share the same name (e.g. merging skill lists from multiple sources without deduplication).

Common situations: Concatenating project-level and user-level skill collections that both define a 'code-reviewer' skill; loading skills from several directories with clashing basenames; generating skills in a loop with a reused name.

Related errors

• No object generated: the model did not return a response.
• maxEmbeddingsPerCall must be greater than 0
• No image generated.
• Duplicate skill name: ${skills[index]!.name}
• ACP credentialEnv and credentialBrokering must be configured

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/5c2aa330230ccccf. Report an issue: GitHub.