mcp-chat-cards

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Create video card

create_video_card

Render a card with an HTML video player for short clips using direct mp4/webm URLs, data URIs, or blob sources. Rejects streaming platform pages to guarantee the video plays.

Instructions

Render a card with an HTML video player for a short clip. src must point straight at a video file (mp4/webm): a direct http(s) URL, a small data:video/* URI, or a blob: URL. Streaming platform page URLs (YouTube, Vimeo, Twitch, TikTok, and similar) are REJECTED, because a video element pointed at a player page renders a card that can never play. When no direct video source exists, use create_animation_card to generate an animated clip instead.

Input Schema

TableJSON Schema

Name	Required	Description
`src`	Yes	Direct http(s) URL to a video file, a data:video/* URI, or a blob: URL
`loop`	No
`muted`	No
`title`	Yes
`poster`	No	Still image shown before playback: http(s) URL or data:image/* URI
`autoplay`	No	Start muted playback on render
`subtitle`	No
`description`	No
`contextActions`	No	Right-click menu actions the model anticipates being useful. Choosing one sends its prompt to the conversation; use {{selection}} to include the user's selected text.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`card`	Yes
`parts`	Yes	Split state, present on EVERY card result so one completeness check works for all card types. Cards that cannot split always report {current:1,total:1,hasMore:false}; create_markdown_card and create_code_tour_card pack oversized content into parts and can report more. Read hasMore rather than the card title to decide whether content was withheld.

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv0.1.3-alphaAug 21, 2026

removedInput schema / $schema

Removed value: -"http://json-schema.org/draft-07/schema#"

removedOutput schema / $schema

Removed value: -"http://json-schema.org/draft-07/schema#"

addedOutput schema / properties / parts

Added value: +{
+  "additionalProperties": false,
+  "description": "Split state, present on EVERY card result so one completeness check works for all card types. Cards that cannot split always report {current:1,total:1,hasMore:false}; create_markdown_card and create_code_tour_card pack oversized content into parts and can report more. Read hasMore rather than the card title to decide whether content was withheld.",
+  "properties": {
+    "current": {
+      "description": "Part number this result rendered (1-based)",
+      "type": "number"
+    },
+    "hasMore": {
+      "description": "True when content was withheld; call again with part: current + 1",
+      "type": "boolean"
+    },
+    "total": {
+      "description": "How many parts the content splits into",
+      "type": "number"
+    }
+  },
+  "required": [
+    "current",
+    "total",
+    "hasMore"
+  ],
+  "type": "object"
+}

changedOutput schema / required

Previous value: -[
-  "card"
-]New value: +[
+  "card",
+  "parts"
+]

Changed7 schema fields changedv0.1.1-alphaAug 12, 2026
- addedInput schema / properties / autoplay
```
Added value: +{
+  "description": "Start muted playback on render",
+  "type": "boolean"
+}
```
- addedInput schema / properties / poster / description
```
Added value: +"Still image shown before playback: http(s) URL or data:image/* URI"
```
- removedInput schema / properties / poster / format
```
Removed value: -"uri"
```
- addedInput schema / properties / poster / minLength
```
Added value: +1
```
- addedInput schema / properties / src / description
```
Added value: +"Direct http(s) URL to a video file, a data:video/* URI, or a blob: URL"
```
- removedInput schema / properties / src / format
```
Removed value: -"uri"
```
- addedInput schema / properties / src / minLength
```
Added value: +1
```
First observedv0.0.0-alphaAug 10, 2026

TDQS

A4.2/5.0

Behavior3/5

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

No annotations were provided, so the description carries the transparency burden. It explains why streaming pages fail (video element pointed at a player page), which is useful behavioral context蓬莱. However, it doesn't mention the output/card format, side effects, or limits on file size. The main behavioral constraint (source type) is well-covered, but other runtime behavior is not described.

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

Conciseness5/5

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

Two sentences. The first immediately states the action and the key constraint. The second explains the rejection rule and points to the alternatve tool. No wasted words.

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

Completeness4/5

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

The description covers the essential constraint on src, which is the most error-prone parameter, and named the sibling tool for animations. It doesn't describe the return value, but an output schema exists. Minor gap: no mention of required vs optional fields like title, but the schema lists required. Good overall.

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

Parameters3/5

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

The schema explains 5 of 9 parameters (src, poster, autoplay, contextActions; loop and muted have only type). The description adds critical detail for src (direct video file only, reject streaming URLs) and ties to the card rendering. That compensates for the low schema coverage on the most important param, but the others remain thin. A middle score is fair.

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 opens with a precise verb and resource: 'Render a card with an HTML video player for a short clip.' It immediately distinguishes the tool from siblings by specifying the target format (video file) and the explicit exclusion of streaming-platform URLs, making the purpose unambiguous.

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?

It states the hard constraint: src must be a direct video file, and explicitly lists what is rejected (streaming URLs) with the reasoning. It also names the alternative tool (create_animation_card) and the condition for using it, so an agent can classify inputs correctly.

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