PrismPoster Creator Tools MCP

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by PrismPoster

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TypeScript

Remote

Estimate video file size and bitrate

estimate_video_bitrate

Read-onlyIdempotent

Plan video exports by calculating file size from bitrate and duration. Determine the required total Kbps to meet a specific file size cap based on resolution and frame rate.

Instructions

Video size and bitrate arithmetic for a clip of durationSec. Pass totalKbps to get the encoded file size (bytes, binary MiB and decimal MB); pass targetBytes to get the highest total bitrate that fits that size; add widthPx, heightPx and fps (with totalKbps) to get bits per pixel, a codec-independent check of whether the bitrate suits the resolution. Kbps is decimal (1 kbps = 1000 bit/s) and covers video plus audio. Use it to plan an export or hit an upload cap; it does not inspect or encode files. Errors when neither totalKbps nor targetBytes is given, or when only some of the bits-per-pixel inputs are.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "durationSec": "<durationSec>"
    },
    "name": "estimate_video_bitrate"
  }
}

Input Schema

Name	Required	Description
`fps`	No	Frame rate, for bits per pixel.
`widthPx`	No	Frame width in px, for bits per pixel.
`heightPx`	No	Frame height in px, for bits per pixel.
`totalKbps`	No	Combined video + audio bitrate in kbps. Needed for file size and bits per pixel.
`durationSec`	Yes	Clip length in seconds.
`targetBytes`	No	File-size cap in bytes (25 MB = 25000000) to solve for the maximum total kbps.

Output Schema

Name	Required	Description	Default
`totalKbps`	Yes
`durationSec`	Yes
`targetBytes`	Yes
`bitsPerPixel`	Yes
`estimatedBytes`	Yes
`formattedBinary`	Yes
`formattedDecimal`	Yes
`referenceToolUrl`	Yes
`targetBitrateKbps`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed16 schema fields changedv1.0.0Oct 24, 2026

addedInput schema / additionalProperties
```
Added value: +false
```

changedInput schema / properties / durationSec / description

Previous value: -"Clip duration in seconds."New value: +"Clip length in seconds."

addedInput schema / properties / durationSec / exclusiveMinimum
```
Added value: +0
```

changedInput schema / properties / fps / description

Previous value: -"Optional frame rate for bits-per-pixel."New value: +"Frame rate, for bits per pixel."

addedInput schema / properties / fps / exclusiveMinimum
```
Added value: +0
```

changedInput schema / properties / heightPx / description

Previous value: -"Optional frame height in pixels for bits-per-pixel."New value: +"Frame height in px, for bits per pixel."

addedInput schema / properties / heightPx / minimum
```
Added value: +1
```

changedInput schema / properties / heightPx / type

Previous value: -"number"New value: +"integer"

changedInput schema / properties / targetBytes / description

Previous value: -"Optional file-size cap in bytes to compute max kbps."New value: +"File-size cap in bytes (25 MB = 25000000) to solve for the maximum total kbps."

addedInput schema / properties / targetBytes / exclusiveMinimum
```
Added value: +0
```

changedInput schema / properties / totalKbps / description

Previous value: -"Total bitrate (video + audio) in kbps (decimal)."New value: +"Combined video + audio bitrate in kbps. Needed for file size and bits per pixel."

addedInput schema / properties / totalKbps / exclusiveMinimum
```
Added value: +0
```

changedInput schema / properties / widthPx / description

Previous value: -"Optional frame width in pixels for bits-per-pixel."New value: +"Frame width in px, for bits per pixel."

addedInput schema / properties / widthPx / minimum
```
Added value: +1
```

changedInput schema / properties / widthPx / type

Previous value: -"number"New value: +"integer"

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "bitsPerPixel": {
+      "type": [
+        "number",
+        "null"
+      ]
+    },
+    "durationSec": {
+      "type": "number"
+    },
+    "estimatedBytes": {
+      "type": [
+        "number",
+        "null"
+      ]
+    },
+    "formattedBinary": {
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "formattedDecimal": {
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "referenceToolUrl": {
+      "type": "string"
+    },
+    "targetBitrateKbps": {
+      "type": [
+        "number",
+        "null"
+      ]
+    },
+    "targetBytes": {
+      "type": [
+        "number",
+        "null"
+      ]
+    },
+    "totalKbps": {
+      "type": [
+        "number",
+        "null"
+      ]
+    }
+  },
+  "required": [
+    "durationSec",
+    "totalKbps",
+    "estimatedBytes",
+    "formattedBinary",
+    "formattedDecimal",
+    "targetBytes",
+    "targetBitrateKbps",
+    "bitsPerPixel",
+    "referenceToolUrl"
+  ],
+  "type": "object"
+}

First observedv0.3.0Oct 23, 2026

TDQS

A5/5.0

Behavior5/5

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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, and the description adds substantial behavioral context beyond them. It documents unit conventions ('kbps is decimal, covers video plus audio') and specific error conditions when inputs are missing or incomplete.

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?

The description is front-loaded with the purpose, then efficiently covers each mode, units, use cases, exclusions, and errors. Every sentence adds actionable information for selecting and invoking the tool.

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?

Given an output schema, the description does not need to explain return values, and it fully covers inputs, modes, units, and failure conditions. Nothing an agent needs in order to call this tool correctly is missing.

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?

Although schema coverage is 100%, the description adds relational meaning the schema alone does not: totalKbps drives file size, targetBytes solves for bitrate, and width/height/fps plus totalKbps enable the bits-per-pixel check. It also clarifies the error case when only some bits-per-pixel inputs are supplied.

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 states a specific verb and resource ('video size and bitrate arithmetic') and identifies the required input ('durationSec'). It clearly distinguishes the tool from file-inspection or encoding tools by saying 'it does not inspect or encode files.'

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 explicitly explains the three usage modes: pass totalKbps for encoded file size, pass targetBytes for maximum bitrate under a cap, and add width/height/fps with totalKbps for bits-per-pixel. It also names concrete use cases ('plan an export or hit an upload cap') and an exclusion ('does not inspect or encode files').

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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