byteplus-seedance-mcp
seedance-mcp
Un servidor MCP que permite a Claude Code generar video con BytePlus ModelArk Dreamina Seedance 2.5.
Pídele a Claude Code un video en lenguaje natural; este envía la tarea a BytePlus, consulta hasta que la renderización finaliza y devuelve la URL del video con los metadatos que BytePlus reporta.
1. Qué hace
Seis herramientas a través de MCP stdio:
Herramienta | Propósito |
| Enviar una tarea de generación. Devuelve un ID de tarea inmediatamente — la generación es asíncrona. |
| Una verificación de estado para una tarea; devuelve la URL del video cuando tiene éxito. |
| Consulta con retroceso hasta que la tarea tenga éxito, falle o se agote el tiempo. |
| Guardar un video finalizado en un archivo local antes de que expire su URL de 24 horas. |
| Cancelar una tarea en cola, o eliminar el registro de una tarea finalizada. |
| Listar tareas recientes, filtrables por estado y modelo. |
Maneja las partes que son fáciles de hacer mal: codificar imágenes y audio locales en la forma de URI de datos Base64 que la API espera, aplicar los límites de parámetros por modelo antes de que se envíe una solicitud, reintentar fallos transitorios con retroceso y mantener la clave API fuera de cada línea de registro y mensaje de error.
Related MCP server: @lweight/xbrush-api-mcp
2. Requisitos previos
Python 3.11+
uv —
brew install uvocurl -LsSf https://astral.sh/uv/install.sh | shClaude Code 2.x
Una cuenta de BytePlus ModelArk con una clave API y el modelo Seedance activado.
3. Configuración de BytePlus
Crear una clave API: Consola de ModelArk → Claves API.
Activar el modelo. Seedance 2.5 no está habilitado por defecto. BytePlus requiere una de:
saldo de cuenta superior a 30 USD, o
un Plan de Ahorro de IA en el nivel de 30 USD o superior, o
un paquete de recursos de Seedance con cuota restante.
Activar en ModelArk → Activación de modelos → Visión por computadora. Sin esto, la creación de tareas falla con un error de autorización aunque la clave en sí sea válida.
Anota tu región. La URL base predeterminada a continuación es
ap-southeast(Singapur). Si tu cuenta está aprovisionada en otro lugar, configuraBYTEPLUS_BASE_URLen consecuencia — una tarea creada en una región no es visible desde otra.
4. Instalación
git clone <this repo> ~/code/seedance-mcp # or just use the directory you already have
cd ~/code/seedance-mcp
uv syncVerificar:
uv run pytest -q # 93 tests, all offline against mocked HTTP
uv run ruff check .5. Configuración de .env
cp .env.example .envLuego completa una variable requerida:
BYTEPLUS_API_KEY=your-modelark-api-keyTodo lo demás es opcional y ya tiene valores predeterminados:
BYTEPLUS_BASE_URL=https://ark.ap-southeast.bytepluses.com/api/v3
SEEDANCE_MODEL_ID=dreamina-seedance-2-5-260628.env está en gitignore. La clave se lee solo del entorno — nunca es escrita en el disco por este servidor, nunca se registra y se elimina de los mensajes de error de la API antes de que lleguen a Claude.
6. Elegir el ID del modelo Seedance 2.5
Seedance 2.5 es un ID de modelo compartido y universalmente disponible — no necesitas crear un endpoint dedicado. El valor predeterminado es:
dreamina-seedance-2-5-260628Nota el prefijo dreamina-. Esta es una inconsistencia real en la nomenclatura de BytePlus: los modelos 2.x Dreamina lo llevan, mientras que los IDs 1.x no (seedance-1-5-pro-251215). Copiar un ID con forma de 1.x para 2.5 es la causa más común de un error "modelo no encontrado".
Confirma el ID actual para tu cuenta en la lista de modelos de ModelArk.
Si prefieres un endpoint dedicado (para límites de tasa por endpoint, facturación prepaga o monitoreo), crea uno en la consola y coloca su ID de endpoint en SEEDANCE_MODEL_ID en su lugar:
SEEDANCE_MODEL_ID=ep-20260817120000-abcde
SEEDANCE_MODEL_PROFILE=seedance-2.5SEEDANCE_MODEL_PROFILE solo es necesario en ese caso: un ID ep-... no dice nada sobre qué modelo está detrás, por lo que sin él, el servidor no puede validar los parámetros localmente y los pasará todos a la API para su validación.
7. Registrar con Claude Code
Desde este directorio (usa la ruta absoluta — Claude Code inicia el servidor desde directorios de trabajo arbitrarios):
claude mcp add \
--transport stdio \
--scope user \
byteplus-seedance \
-- uv --directory /Users/alban/code/seedance-mcp run python -m seedance_mcp--scope user lo hace disponible en cada proyecto. Usa --scope project para compartirlo con los colaboradores de un repositorio a través de .mcp.json, u omite --scope solo para el proyecto actual.
El servidor lee .env desde su propio directorio, por lo que no se necesitan banderas -e. Si prefieres pasar la clave explícitamente:
claude mcp add --scope user byteplus-seedance \
-e BYTEPLUS_API_KEY=your-key \
-- uv --directory /Users/alban/code/seedance-mcp run python -m seedance_mcp8. Verificación
claude mcp listEspera una línea como:
byteplus-seedance: uv --directory /Users/alban/code/seedance-mcp run python -m seedance_mcp - ✓ ConnectedLuego dentro de Claude Code, /mcp lista el servidor y sus seis herramientas. Pídele:
Lista mis tareas recientes de Seedance.
Eso prueba la autenticación y la conectividad sin gastar créditos de generación — una lista vacía es un éxito. Si la clave es incorrecta, recibirás un mensaje explícito de HTTP 401.
Para una verificación de extremo a extremo que realmente renderice un archivo, usa la receta de costo mínimo en §10.
9. Ejemplos de indicaciones para Claude Code
Generate a 10-second 1080p cinematic video of Tokyo at night using Seedance 2.5.Use ./assets/reference.png as the visual reference and generate a slow cinematic push-in shot.Create the video and wait until generation finishes.Generate a 15-second 9:16 vertical clip of a surfer at sunrise, no audio, and give me the URL.Use ./assets/first.png as the first frame and ./assets/last.png as the last frame,
6 seconds, and wait for it.Check the status of task cgt-20260817... and download the video if it's ready.Download task cgt-20260818061514-8t2lv into ./renders/ and keep the last frame too.Cancel task cgt-20260817... — I queued the wrong prompt.10. Costo y tiempo
La generación se factura por segundo de salida, escalada por resolución y modelo. La forma más barata de probar que el pipeline funciona es un clip de 4 segundos a 480p — 4s es la duración más corta que acepta cualquier modelo Seedance 2.x.
Verificación gratuita, sin gastar créditos de generación:
List my recent Seedance tasks.Generación real más barata. Seedance 2.0 mini es el modelo menos costoso en la cuenta; durante la promoción vigente hasta el 7 de septiembre de 2026, su salida a 720p comienza alrededor de 0.03 USD/segundo, y 480p está por debajo de eso:
Using Seedance model seedance-2-0-mini-260615, generate a 4-second 480p video, 16:9, no audio,
prompt: "a red balloon floating up against a blue sky". Then wait for it and give me the URL.Prueba más barata de la ruta predeterminada de Seedance 2.5 — vale la pena ejecutarla por separado, ya que 2.5 es una activación de modelo diferente y un nivel de precio diferente:
Generate a 4-second 480p Seedance 2.5 video, 16:9, no audio,
prompt: "a red balloon floating up against a blue sky". Wait for it and give me the URL.Línea base medida
De una ejecución real de Seedance 2.5 de texto a video el 18 de agosto de 2026:
Salida | Tiempo real | Uso reportado |
4s · 480p · 16:9 · 24 fps · sin sonido | ~105 s | 38,830 tokens |
Ese es el mínimo: la duración más corta con la resolución más baja y sin material de referencia. También establece expectativas para seedance_wait_for_video, cuyo tiempo de espera predeterminado de 900 segundos está dimensionado para trabajos un orden de magnitud más pesados que este.
Escalar a partir de esa línea base es extrapolación, no medición — el uso sigue los segundos de salida y el recuento de píxeles, por lo que un clip de 10 segundos a 1080p es aproximadamente 2.5× los segundos y ~5× los píxeles, es decir, del orden de 10× esta ejecución. Trátalo como una estimación de planificación y confírmalo con tu propia facturación.
La trampa del costo de duration
Seedance 2.5 establece duration por defecto en -1, lo que permite que el modelo elija cualquier duración de hasta 30 segundos. Dado que la facturación es por segundo de salida, una solicitud que no indique una duración puede costar alrededor de 7 veces una prueba prevista de 4 segundos. Indica el número de segundos explícitamente en cualquier ejecución sensible al costo — la herramienta lo pasa directamente, y 4 es el mínimo.
Dos notas menores: 480p y 720p están excluidas del descuento promocional actual de 2.5 (solo 1080p tiene descuento), por lo que 480p sigue siendo la más barata en términos absolutos — el descuento simplemente no se aplica. Y sin sonido principalmente acorta el tiempo de generación; nada en la documentación muestra que reduzca el precio.
11. Solución de problemas
Síntoma | Causa y solución |
| No hay |
| Clave incorrecta o revocada, o una clave de una cuenta de BytePlus diferente a la que tiene la activación del modelo. |
| La tarea se creó en una región diferente, o tiene más de 7 días (BytePlus purga los registros de tareas después de 7 días). |
Modelo no encontrado al crear |
|
| Límite de tasa superado. El cliente ya reintenta con retroceso y respeta |
| Esperado. BytePlus acepta video de referencia solo como una URL pública o ID |
La tarea falla con | Seedance 2.5 infirió un tipo de tarea diferente al que permiten tus parámetros. Establece |
| Las URLs de salida caducan 24 horas después de la finalización, y las URLs de Seedance 2.5 permiten como máximo 100 descargas. Vuelve a generar, o configura la suscripción de datos TOS de BytePlus para almacenamiento duradero. Usa |
| Protege contra sobrescribir una renderización anterior. Pasa |
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El servidor aparece como fallido en | Ejecuta el comando manualmente — |
12. Funciones compatibles de Seedance 2.5
Tipos de tarea (mutuamente excluyentes — BytePlus rechaza mezclas):
Texto a video — solo indicación.
Imagen a video —
first_frame, opcionalmente máslast_frame. La salida comienza y termina exactamente en esas imágenes.Referencia omni a video — hasta 30 imágenes de referencia, 10 videos de referencia y 10 clips de audio, con entrada solo de audio permitida. Cita activos en la indicación como
@Image 1,@Video 2. Cubre tres subtareas: referencia a video, edición de video y extensión de video — dirígelas conomni_reference_task_type.
Controles de salida
Parámetro | Valores de Seedance 2.5 |
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Entradas de medios
Tipo | Formatos | Límite por archivo | Soporte de archivos locales |
Imagen | jpeg, png, webp, bmp, tiff, gif, heic, heif | 30 MB | ✅ incrustado como Base64 |
Audio | wav, mp3 | 15 MB | ✅ incrustado como Base64 |
Vídeo | mp4, mov | 200 MB | ❌ solo URL pública o |
Los prompts funcionan en inglés, español, indonesio, portugués, japonés, malayo, tailandés, árabe, vietnamita y coreano. Mantenlos por debajo de ~1000 palabras en inglés.
Guardar la salida. seedance_download_video toma un ID de tarea, busca la URL actual por sí mismo y
transmite el archivo al disco. Por defecto a ./<task_id>.mp4; pasa una ruta de archivo o un directorio existente
como output_path. Nunca sobrescribe sin overwrite: true, limpia archivos parciales si una
descarga se interrumpe, y también puede obtener el PNG final con include_last_frame cuando la tarea se creó
con return_last_frame. Dos restricciones deliberadas: las descargas se realizan a través de su propio
cliente HTTP no autenticado, por lo que la clave de ModelArk nunca se envía al host de almacenamiento, y el host
de la URL debe terminar en .volces.com, .bytepluses.com o .byteplus.com — este es un extractor de salida de Seedance,
no un descargador de propósito general.
El servidor también apunta a modelos más antiguos mediante el argumento de herramienta model o SEEDANCE_MODEL_ID —
Seedance 2.0 / 2.0 fast / 2.0 mini, 1.5 pro, 1.0 pro y 1.0 pro fast — validando cada uno contra sus
propios límites (por ejemplo, 4K es válido en 2.0 pero no en 2.5).
13. Limitaciones conocidas de la API
La generación es asíncrona. Nada devuelve un vídeo de forma síncrona; un clip de 5 a 10 segundos normalmente tarda unos minutos, más en 1080p.
No se puede establecer
seednicamera_fixeden Seedance 2.5. La referencia actual de la API enumera ambos como parámetros de entrada solo para Seedance 1.5 pro, 1.0 pro y 1.0 pro fast. Este servidor los rechaza para 2.5 con un mensaje explícito en lugar de descartarlos silenciosamente. Expresa el comportamiento de la cámara en el prompt en su lugar. (Los tutoriales antiguos de Seedance 1.x y ejemplos de terceros aún muestran estos parámetros — ya no se aplican a 2.5.)Observado en una ejecución real de 2.5: la respuesta de la tarea aún informa un
seed(mostrado comoVideoResult.seed, p. ej.80969), porque el modelo elige uno internamente. Así que puedes ver qué semilla produjo un clip, pero no puedes pedirla de nuevo — las generaciones de 2.5 no son reproducibles.No hay
framesen Seedance 2.5. Las duraciones de subsegundo mediante el recuento de fotogramas son una característica de 1.0 pro.No se puede subir vídeo local. Las imágenes y el audio tienen una forma Base64; el vídeo no.
Límite de 64 MB en el cuerpo de la solicitud. Incrustar varias imágenes grandes lo alcanzará; el servidor lo comprueba antes de enviar y te indica que cambies a URLs.
Los rostros humanos reales están restringidos. Seedance 2.x rechaza imágenes de referencia y vídeos que contengan rostros humanos reales a menos que sean una salida previa de Seedance de tu propia cuenta (dentro de 30 días), un personaje digital predefinido o un activo de persona real autorizado.
Solo se pueden cancelar las tareas en cola. Una vez que una tarea está en ejecución, se ejecuta hasta completarse.
Las URLs de salida viven 24 horas, con un límite de 100 descargas en Seedance 2.5. Ambos límites están integrados en la propia URL firmada — un enlace devuelto lleva
X-Tos-Expires=86400yX-Tos-Max-Requests=100. No hay un punto final de reemisión, yseedance_list_taskssolo puede devolver una URL que aún esté dentro de esa ventana. Usaseedance_download_videopara guardar cualquier cosa que valga la pena conservar; una vez que la ventana se cierra, el único remedio es generar de nuevo.Los registros de tareas viven 7 días.
Los límites de duración de los medios de referencia no se verifican localmente. Los límites por clip (2–30 s) y total (30 s) para vídeo y audio de referencia necesitan sondeo de medios; el servidor no agrega una dependencia de decodificador para ello, por lo que BytePlus los aplica y los informa como errores de tarea.
Los precios y las restricciones cambian. La tabla de capacidades en
src/seedance_mcp/capabilities.pyfue transcrita de la documentación de BytePlus el 2026-08-17; revísala si BytePlus lanza una nueva revisión del modelo.
14. Estructura del proyecto
seedance-mcp/
├── pyproject.toml
├── README.md
├── .env.example
├── .gitignore
├── src/seedance_mcp/
│ ├── __init__.py
│ ├── __main__.py # stdio entry point
│ ├── server.py # the six MCP tools
│ ├── client.py # BytePlus HTTP client: retries, error parsing
│ ├── payload.py # request building + validation
│ ├── capabilities.py # per-model limits from the official docs
│ ├── media.py # local file -> data URI, with validation
│ ├── models.py # typed request/response models
│ ├── config.py # environment configuration
│ └── errors.py # error types + secret redaction
└── tests/capabilities.py, payload.py y media.py son adiciones al diseño esbozado en el resumen:
la tabla de restricciones por modelo documentada, el constructor de solicitudes y el manejo de medios tienen cada uno
lógica real y sus propias pruebas, y fusionarlos en server.py o models.py habría hecho que ambos
fueran difíciles de leer.
15. Fuentes
Cada detalle de la API anterior fue verificado con la documentación oficial actual de BytePlus:
Available Tools
6 toolsseedance_cancel_videoCancel or delete a Seedance taskA
Cancel a Seedance task that is still queued, or delete the record of one that already finished. BytePlus maps both to a single DELETE call. Only queued tasks can actually be cancelled - a task already running cannot be stopped, and the call will fail. Cancelled tasks are purged after 24 hours.
| Name | Required | Description | Default |
|---|---|---|---|
| task_id | Yes | Task ID to cancel or delete. |
Output Schema
| Name | Required | Description |
|---|---|---|
| note | Yes | |
| task_id | Yes | |
| cancelled | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, so description carries the full burden. It discloses the underlying HTTP method (DELETE), the fact that only queued tasks can truly be cancelled, that calls on running tasks fail, and the post-cancellation purge delay. It does not cover idempotency or behavior when task_id does not exist, but the output schema likely handles error responses. Overall, good transparency for a simple cancellation tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three sentences total. First sentence immediately states the dual purpose. Second sentence explains the key behavioral limitation. Third sentence adds lifecycle context. No wasted words, front-loaded with essential information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with one required parameter and clear cancellation semantics, the description covers the operation's dual nature, failure cases for running tasks, and post-cancellation cleanup. An output schema exists (though not shown), so return value explanation is not needed. The description is complete for the complexity level.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 100% description coverage—task_id is described as 'Task ID to cancel or delete.' The tool description does not add any additional semantics (e.g., format, source, or validation). Since the schema already provides the meaning, the description offers no extra value, meeting the baseline of 3.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it cancels queued tasks or deletes finished records, using the verb 'cancel or delete' and the resource 'Seedance task'. It distinguishes between the two states, providing specific scope. The sibling tools (create, get, wait, download, list) further clarify this is the cancellation tool.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly says when to use: for queued tasks (cancel) or finished ones (delete). Provides a critical caveat that running tasks cannot be stopped and the call will fail. Mentions that cancelled tasks are purged after 24 hours. Lacks explicit alternatives (e.g., no mention of what to do if you need to stop a running task), but the tool set doesn't include such an option, so the guidance is adequate.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
seedance_create_videoCreate a Seedance video generation taskA
Start a Seedance video generation task on BytePlus ModelArk and return its task ID. Generation is ASYNCHRONOUS and takes minutes: this tool returns immediately without a video. Follow it with seedance_wait_for_video (blocks until the video is ready - use this when the user just wants the video) or seedance_get_video (single status check).
Choose exactly ONE input shape; BytePlus rejects mixtures:
text-to-video: prompt only.
image-to-video: first_frame (+ optional last_frame) - the output starts (and ends) on those exact frames.
omni reference-to-video: image_references / video_references / audio_references - the model borrows subjects, style, motion or sound from them. Seedance 2.5 accepts up to 30 images, 10 videos and 10 audio clips, and can run on audio alone. Refer to them in the prompt as '@Image 1', '@Video 2' etc. first_frame/last_frame cannot be combined with the *_references parameters.
Media may be a local file path, a public https:// URL, or an asset://. Local images (jpeg, png, webp, bmp, tiff, gif, heic, heif; max 30 MB) and local audio (wav, mp3; max 15 MB) are inlined automatically. Local VIDEO files cannot be uploaded - BytePlus takes reference video only as a public URL, so host it first.
Seedance 2.5 supports resolution 480p/720p/1080p, ratio 16:9/4:3/1:1/3:4/9:16/21:9/adaptive, and duration 4-30 seconds (or -1 to let the model choose). It does NOT support seed or camera_fixed - describe camera moves in the prompt instead.
| Name | Required | Description | Default |
|---|---|---|---|
| seed | No | Randomness seed, -1 to 2147483647. Supported by Seedance 1.5 pro and 1.0 pro only - NOT by Seedance 2.5. | |
| model | No | Override the configured model ID or endpoint ID for this call, e.g. 'dreamina-seedance-2-5-260628'. Omit to use the server default. | |
| ratio | No | Aspect ratio: '16:9', '4:3', '1:1', '3:4', '9:16', '21:9' or 'adaptive'. Default 'adaptive'. Must be 'adaptive' for first_frame/last_frame tasks and for video edit/extend tasks. | |
| prompt | No | What to generate: subject, action, setting, camera movement, lighting, mood. Put spoken dialogue in double quotes to drive the generated audio. Keep it under ~1000 English words. Required unless media references are supplied. | |
| duration | No | Output length in seconds. Seedance 2.5: 4-30, or -1 to let the model pick. Omit to use the model default. | |
| watermark | No | Add an 'AI Generated' watermark in the lower-right corner. | |
| last_frame | No | Image the video must end on. Requires first_frame. | |
| resolution | No | '480p', '720p' or '1080p' on Seedance 2.5. Default 720p. | |
| first_frame | No | Image the video must start on (local path, https:// URL, or asset://<ID>). Mutually exclusive with the *_references parameters. | |
| callback_url | No | HTTPS endpoint BytePlus POSTs to when the task status changes. | |
| camera_fixed | No | Lock the camera. Supported by Seedance 1.5 pro and 1.0 pro only - NOT by Seedance 2.5, where camera behaviour belongs in the prompt. | |
| service_tier | No | 'default' for online inference, or 'flex' for cheaper offline runs. | |
| generate_audio | No | Whether the output carries synchronised sound (voices, effects, music). Defaults to true on Seedance 2.5; pass false for a silent video. | |
| audio_references | No | Reference audio (wav/mp3) to drive speech, music or timing. Seedance 2.5: up to 10, each 2-30s, 30s total, and audio-only input is allowed. | |
| image_references | No | Reference images for an omni reference-to-video task (subject, character or style guidance). Seedance 2.5: up to 30. Cite them in the prompt as '@Image 1'. | |
| video_references | No | Reference videos, as public https:// URLs or asset://<ID> only (local video files cannot be uploaded). Seedance 2.5: up to 10, each 2-30s, 30s total. Cite them in the prompt as '@Video 1'. | |
| return_last_frame | No | Also return the final frame as a PNG, so it can seed the next clip's first_frame for a continuous sequence. | |
| omni_reference_task_type | No | Seedance 2.5 only, and only with reference media. 'edit' to modify a reference video (requires ratio 'adaptive' and duration -1), 'extend' to continue one (requires ratio 'adaptive'), or 'auto'. Setting it moves validation to submit time instead of failing asynchronously mid-generation. |
Output Schema
| Name | Required | Description |
|---|---|---|
| model | Yes | |
| status | Yes | Task state at submission time; always pending server-side. |
| request | Yes | |
| task_id | Yes | |
| next_step | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Without any annotations provided, the description carries full burden and does well: declares asynchronous gen, delays minutes, returns task ID immediately. It explains that BytePlus rejects mixed input shapes, details media upload rules (local images inlined, local videos not supported), and notes model-specific behaviors (Seedance 2.5 doesn't support seed/camera_fixed). Minor gap: doesn't describe error behavior if a reference is invalid.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Description is well-structured with clear sections: async behavior first, then three input shapes, then media constraints, then parameter notes. It front-loads the most critical info (async return, sibling tool guidance). It is somewhat long but every sentence earns its place for a complex tool with 18 parameters. Could be slightly tighter by combining repeated mentions of model version constraints.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a high-complexity tool with 18 parameters and no annotations, the description covers all essential aspects: the three input shapes and mutual exclusivity, the async behavior, sibling tool workflow, media upload rules per type, model-specific limitations (Seedance 2.5 param constraints, max counts), citation syntax, and special parameters (return_last_frame chaining). The output schema exists, so return values are covered separately.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% so baseline is 3; the description adds significant value by grouping parameters into three mutually exclusive shapes, explaining relationships (first_frame mutually exclusive with *_references), detailing citation syntax (@Image 1, @Video 2), specifying upload constraints per parameter type, and clarifying model-specific constraints (seed, camera_fixed not for 2.5). Some schema descriptions already include individual parameter details, but the description's structural insight exceeds schema alone.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it starts a Seedance video generation task, returns a task ID, and explicitly distinguishes the asynchronous nature from sibling tools like seedance_wait_for_video. It precisely describes three input shapes (text-to-video, image-to-video, omni reference-to-video) with exact parameter combinations, making it unambiguous what the tool does.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
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 this tool vs. alternatives: states it is asynchronous and returns immediately, then instructs agents to follow with seedance_wait_for_video (when user wants video) or seedance_get_video (single check). It also explains that media fields have different constraints (local images vs. public URLs for videos), which directly affects tool selection and parameter setup.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
seedance_download_videoDownload a finished Seedance videoA
Save a finished Seedance video to a local file. Use this whenever the user wants to keep the video rather than just see a link: output URLs expire 24 hours after the task completes and allow only 100 downloads, and BytePlus cannot re-issue them. Pass the task_id - the tool looks up the current URL itself, so it works on any task that succeeded within the last 24 hours. The task must be in 'succeeded' state. Without output_path the file is written to the current directory as <task_id>.mp4. An existing file is never overwritten unless overwrite is true. Set include_last_frame to also save the closing PNG, which is only available if the task was created with return_last_frame.
| Name | Required | Description | Default |
|---|---|---|---|
| task_id | Yes | ID of a succeeded task, e.g. 'cgt-20260818061514-8t2lv'. | |
| overwrite | No | Replace the file if it already exists. | |
| output_path | No | Where to save it: a file path, or an existing directory to save <task_id>.mp4 inside. Defaults to the current directory. | |
| include_last_frame | No | Also save the last-frame PNG, if the task was created with return_last_frame. |
Output Schema
| Name | Required | Description |
|---|---|---|
| note | No | |
| source | Yes | |
| size_mb | Yes | |
| task_id | No | |
| file_path | Yes | Absolute path of the saved video. |
| resolution | No | |
| bytes_written | Yes | |
| last_frame_path | No | |
| duration_seconds | No |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description fully carries the burden. It discloses critical behaviors: output URLs expire after 24 hours and allow only 100 downloads (no reissue), the tool looks up the current URL itself, file is written to current directory if no path given, existing files are never overwritten unless overwrite=true, and include_last_frame requires the task to have been created with return_last_frame.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is about 100 words, well-structured with the primary purpose first, followed by usage context and parameter details. Every sentence adds value, no redundancy or filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the 4 parameters and full schema coverage, the description is complete. It explains prerequisites (task must be succeeded, within 24h), file handling rules, optional behavior (include_last_frame condition), and the self-service nature of URL resolution. An output schema exists but the description correctly focuses on usage context rather than return format.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, giving a baseline of 3. The description adds value beyond the schema by explaining that output_path defaults to current directory for <task_id>.mp4, that existing files are never overwritten without explicit overwrite=true, and that include_last_frame requires the original task to have return_last_frame. These details clarify default behavior and preconditions not obvious from parameter descriptions alone.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool saves a finished Seedance video to a local file, with the specific verb 'Save' and resource 'finished Seedance video'. It distinguishes from siblings like seedance_get_video (just view link) by explaining when to use it for permanent storage rather than just seeing a link.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly says to use this when the user wants to keep the video rather than just a link, and mentions URL expiration and download limits. It also states the task must be in 'succeeded' state. While it doesn't explicitly name alternative tools, the context of sibling names and the 'use this whenever' phrasing provides clear guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
seedance_get_videoCheck a Seedance taskA
Check a Seedance generation task once and return its current state. Use this for a quick status poll; if the user is waiting for the finished video, use seedance_wait_for_video instead of calling this in a loop. Status is one of queued, running, succeeded, failed, cancelled, expired. On success the result carries video_url (valid 24 hours), plus the resolution, aspect ratio, duration and frame rate BytePlus actually produced. On failure it carries error_code and error_message. Task records are kept for 7 days.
| Name | Required | Description | Default |
|---|---|---|---|
| task_id | Yes | Task ID from seedance_create_video, e.g. 'cgt-20260817...'. |
Output Schema
| Name | Required | Description |
|---|---|---|
| fps | No | |
| note | No | |
| seed | No | |
| model | No | |
| polls | No | |
| ratio | No | |
| frames | No | |
| status | Yes | |
| task_id | Yes | |
| video_url | No | Valid for 24 hours; Seedance 2.5 URLs allow 100 downloads. |
| created_at | No | |
| error_code | No | |
| resolution | No | |
| updated_at | No | |
| is_terminal | Yes | |
| total_tokens | No | |
| error_message | No | |
| generate_audio | No | |
| last_frame_url | No | |
| waited_seconds | No | |
| duration_seconds | No |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Although no annotations are provided, the description fully discloses the tool's behavior: it performs a single check, returns current state, and lists all possible statuses. It details the result structure (on success: video_url with 24h validity, resolution, aspect ratio, duration, frame rate; on failure: error_code and error_message). It also mentions task retention policy (7 days). The only minor gap is no explicit mention of whether it's a mutation or read-only operation, but the context strongly implies a safe read.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is three sentences, each earning its place: the first states the core purpose, the second provides usage guidance and an alternative, and the third details the response format and lifecycle. No fluff, perfectly front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the low complexity (1 parameter, all required, no enums, 100% schema coverage), the tool is simple. The description covers the input (task_id), behavior (single poll, no looping), output (with detailed success/failure fields, plus video URL validity), and retention policy. An output schema exists, but the description still summarizes the key fields, which is helpful. No gaps remain for an agent to misinterpret.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100% (the only parameter task_id has a clear description in the schema). The description adds limited additional semantic value beyond the schema, as the schema already explains it's the task ID from seedance_create_video with an example format. However, the description could have elaborated on how to obtain the task_id, but it's mostly sufficient.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states 'Check a Seedance generation task once and return its current state.' It specifies the verb (check), resource (Seedance generation task), and action scope (once). The tool is well-differentiated from siblings like seedance_wait_for_video, which is explicitly mentioned as the alternative for polling.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly tells when to use this tool ('quick status poll') and when not to ('if the user is waiting for the finished video, use seedance_wait_for_video instead of calling this in a loop'). It provides clear guidance on avoiding loops, which is critical for agent behavior.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
seedance_list_tasksList recent Seedance tasksA
List recent Seedance generation tasks for this account, newest first, optionally filtered by status or model. Useful to recover a task ID that was lost, to check what is still queued, or to re-fetch a video URL for a task that finished within the last 24 hours. BytePlus keeps task records for 7 days.
| Name | Required | Description | Default |
|---|---|---|---|
| model | No | Filter by model ID or endpoint ID. | |
| status | No | Filter by state: queued, running, succeeded, failed, cancelled or expired. | |
| page_num | No | 1-based page number. | |
| page_size | No | Results per page. |
Output Schema
| Name | Required | Description |
|---|---|---|
| tasks | Yes | |
| total | No | |
| page_num | Yes | |
| page_size | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden for behavioral disclosure. It clearly states the tool is read-only (listing tasks), notes the data retention period (7 days), and explains that finished tasks' video URLs are only fetchable within 24 hours. The only gap is that it doesn't explicitly mention it's non-destructive, but the listing action implies this.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is three sentences long and front-loaded with the core purpose. The first sentence states action, scope, ordering, and optional filters. The second provides concrete use cases. The third covers data retention. Every sentence serves a distinct informative purpose with no repetition or filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool has no required parameters, a fully described schema (4 params, 100% coverage), an output schema (not shown but present), and clear behavioral context (retention, ordering, use cases), the description leaves no critical gaps. It is complete for an agent to decide when and how to invoke the tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% and each parameter's description is clear (model ID/endpoint ID filtering, status enum, page number/page size with bounds). The description adds context by noting common use cases (filter by status, model) but does not elaborate beyond what the schema provides. Since coverage is high, baseline 3 is appropriate, and the additional context bumps it to 4.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly specifies the action ('List recent Seedance generation tasks'), the scope ('for this account'), ordering ('newest first'), and optional filtering by status or model. It also explicitly distinguishes the tool from siblings like seedance_create_video or seedance_get_video by focusing on listing tasks rather than creating or retrieving individual videos.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
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 this tool: to recover a lost task ID, check queued tasks, or re-fetch a video URL within 24 hours. It also mentions the retention policy (7 days), setting clear boundaries on expected results. No sibling tool duplicates this list behavior, so exclusion criteria are implied.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
seedance_wait_for_videoWait for a Seedance video to finishA
Poll a Seedance task until it succeeds, fails, or the timeout elapses, then return the final result including the video URL. Call this right after seedance_create_video whenever the user wants the finished video rather than a task ID. Polling backs off automatically. A 5-10 second clip usually lands within a few minutes; long or 1080p jobs take longer, so raise timeout_seconds for those. A timeout does not cancel anything - the task keeps running and can be waited on again.
| Name | Required | Description | Default |
|---|---|---|---|
| task_id | Yes | Task ID from seedance_create_video. | |
| timeout_seconds | No | Give up after this many seconds. Default 900 (15 minutes). | |
| raise_on_failure | No | Raise an error when the task ends in failed/cancelled/expired. Set false to get the failure details as a normal result instead. | |
| poll_interval_seconds | No | Initial delay between checks; it backs off from here. |
Output Schema
| Name | Required | Description |
|---|---|---|
| fps | No | |
| note | No | |
| seed | No | |
| model | No | |
| polls | No | |
| ratio | No | |
| frames | No | |
| status | Yes | |
| task_id | Yes | |
| video_url | No | Valid for 24 hours; Seedance 2.5 URLs allow 100 downloads. |
| created_at | No | |
| error_code | No | |
| resolution | No | |
| updated_at | No | |
| is_terminal | Yes | |
| total_tokens | No | |
| error_message | No | |
| generate_audio | No | |
| last_frame_url | No | |
| waited_seconds | No | |
| duration_seconds | No |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It covers key behaviors: polling with automatic backoff, timeout behavior (doesn't cancel), typical time estimates, and return of final result including video URL. It does not mention rate limits or auth requirements, but for a polling tool this is reasonable. The description adds value beyond what structured metadata could provide.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is three sentences long, each earning its place: the first states the core action, the second specifies when to use it, and the third provides critical usage guidance. It is front-loaded with the most important information and contains no filler or redundant phrases.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers the main purpose, usage context, timeout behavior, and auto-backoff. An output schema exists, so return value details are handled there. However, it does not explicitly differentiate from 'seedance_get_video' (if that tool exists for non-polling status checks). Given the tool's polling nature and the presence of other sibling tools, the description is nearly complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema has 100% description coverage, so each parameter already has a clear explanation. The description adds some context (e.g., 'task ID from seedance_create_video', timing guidance for timeout_seconds) but does not significantly enhance understanding of parameters beyond what the schema provides. Baseline of 3 is appropriate since the schema does most of the work.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states that the tool polls a Seedance task until completion or timeout and returns the final result including the video URL. It explicitly differentiates from siblings by specifying when to call it: 'right after seedance_create_video whenever the user wants the finished video rather than a task ID.' The title also reinforces the purpose.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
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 the tool ('Call this right after seedance_create_video...') and includes practical advice about adjusting timeout for longer jobs. It also clarifies that a timeout does not cancel the task and that the task can be waited on again. However, it does not explicitly state when not to use it or mention alternative sibling tools for different use cases.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
6 tool updates
v0.1.0- First observed
seedance_cancel_video - First observed
seedance_create_video - First observed
seedance_download_video - First observed
seedance_get_video - First observed
seedance_list_tasks - First observed
seedance_wait_for_video
TDQS
Scored across 6 tools
Each tool serves a distinct purpose: creating, checking status, waiting, downloading, canceling, and listing tasks. There is no overlap, and the descriptions clearly differentiate their use cases.
All tools follow a consistent verb_noun pattern prefixed with 'seedance_': create_video, get_video, wait_for_video, download_video, cancel_video, list_tasks. No mixing of conventions.
With 6 tools, the set is well-scoped for a video generation service. It covers the necessary operations without being too sparse or bloated.
The tool surface covers the full lifecycle: creation, monitoring (with two convenient patterns), output retrieval, cancellation/deletion, and history listing. No obvious gaps for the intended domain.
Maintenance
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