Workflow tool: object passed as `args` arrives in the script as a JSON-encoded string

Environment

• Claude Code CLI, model claude-fable-5, Linux (Arch, 6.18.22-1-lts)
• Workflow tool (multi-agent orchestration)

Symptom

Passing a JSON object in the Workflow tool call's args parameter delivers a JSON-encoded string to the script's args global. A script doing args.worktrees.map(...) crashes:

Error: undefined is not an object (evaluating 'worktrees.map')

The failure notification's recovery hint itself shows the value string-wrapped: args: "{\"worktrees\":[...]}" — i.e. the object was serialized somewhere between the tool call and the script sandbox.

Why it matters

The tool description explicitly instructs: "Pass arrays/objects as actual JSON values in the tool call, NOT as a JSON-encoded string — a stringified list reaches the script as one string, so args.filter/args.map throw." The model complies, but the harness stringifies anyway, so every args-driven workflow fails on first run.

Workaround

Guard at the top of every script:

const input = typeof args === 'string' ? JSON.parse(args) : args

(Resume with resumeFromRunId after patching works fine.)

Suggested fix

Either deliver args verbatim as parsed JSON into the script sandbox, or (defensively) auto-JSON.parse in the runtime when args is a string that parses as JSON — matching the documented contract.

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