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video_workflow_render

Executes video workflow job specifications, running operations like trim, resize, convert, and merge. Supports variant rendering, resumption, and batch processing.

Instructions

Execute an agent workflow job-spec and return a provenance receipt.

Validates the spec first (fail-closed), then runs each allowlisted op (probe|trim|resize|convert|merge|add_text|composite_layers) SEQUENTIALLY in spec order via the backing engine functions. Intermediates are written to a per-run @work directory unique to this invocation and cleaned on success (kept on failure); final media lands at the declared @outputs paths.

Batch variants: pass variant=<id> to render one declared variant (its overrides patch the shared steps/outputs, and the single @outputs path is auto-named with the variant id so N variants emit N distinct outputs); the receipt records workflow.variant. Pass all_variants=True to render EVERY declared variant in turn and return a workflow_batch summary (one receipt per variant, each into its own @work dir); use save_receipt_dir to also write each variant's receipt to <dir>/<variant>.json. variant and all_variants are mutually exclusive. Pass keep_intermediates=True to retain @work intermediates even on success (recorded as the keep-intermediates cleanup policy).

Pass resume_receipt (a prior render receipt from a job that failed with its intermediates kept) to RESUME: the current spec_hash must equal the receipt's (else fail-closed resume_spec_mismatch) AND, for a variant, the receipt's variant must match (else resume_variant_mismatch); each step whose recorded status is completed AND whose recorded input hashes still match AND whose recorded output file still exists and re-hashes to the recorded hash is SKIPPED, and the first step failing any check plus everything after it re-runs.

Returns a workflow receipt (receipt_kind: "workflow") capturing tool + FFmpeg versions, the spec hash, per-source probes/hashes, per-step status with real sha256 hashes of every consumed input and produced output, the cleanup manifest, and the determinism-scope caveat. On the first failing step it fails closed: the failure is recorded on the receipt (still written to save_receipt when given) and surfaced as a structured error.

Args: spec_path: Absolute path to the workflow job-spec JSON file. resume_receipt: Optional path to a prior render receipt to resume from. save_receipt: Optional path to write the workflow receipt as JSON. keep_intermediates: Retain @work intermediates even on success. variant: Optional declared variant id to render a single variant. all_variants: Render every declared variant and return a batch summary. save_receipt_dir: With all_variants, directory for per-variant receipts.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
variantNo
spec_pathYes
all_variantsNo
save_receiptNo
resume_receiptNo
save_receipt_dirNo
keep_intermediatesNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description bears full burden and fully discloses behaviors: validation fail-closed, sequential op execution, intermediate cleanup policy, resume logic with hash matching, variant handling, and return receipt structure. No contradictions.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is comprehensive and well-structured with clear sections, but it is somewhat lengthy. While every sentence adds value, it could be slightly more concise by moving some parameter details to the schema. However, it remains well-organized.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description is highly complete, covering purpose, parameters, behavior, return value (workflow receipt), error handling (fail closed), edge cases (resume, variant, batch), and cleanup. Despite the presence of an output schema (not shown), the description does not rely on it and provides full context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, but the description contains an 'Args:' section that explains each parameter (spec_path, resume_receipt, etc.) in detail, including constraints like mutual exclusivity and default behavior. This fully compensates for the schema's lack of descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'Execute' the resource 'agent workflow job-spec' and the result 'provenance receipt'. It distinguishes from sibling tools like video_workflow_plan (planning) and video_workflow_validate (validation) by focusing on execution and rendering.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit guidance on when to use variant vs all_variants, their mutual exclusivity, how to resume from a failed receipt, and the keep_intermediates option. It also explains the sequential execution order and fail-closed behavior, giving clear context for selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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