justcaptions

estimate_video

Read-onlyIdempotent

Estimate cloud transcription costs before processing by measuring audio locally; provide text_chars for editing or translation, or that cost is excluded.

Instructions

Estimate cloud cost before transcription. Audio is measured locally; supply known text_chars for editing/translation, otherwise their cost is excluded. Does not reserve credit.

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": {
      "input_path": "<input_path>"
    },
    "name": "estimate_video"
  }
}

Input Schema

Name	Required	Description	Default
`input_path`	Yes
`text_chars`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.4.0Oct 7, 2026

TDQS

A3.9/5.0

Behavior4/5

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

Annotations already establish readOnly/idempotent/non-destructive, but the description adds non-obvious facts beyond them: that audio is measured locally and that no credit is reserved. The 'does not reserve credit' detail is exactly the kind of side-effect clarification an agent needs and is not derivable from the annotations.

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?

Three tight sentences; purpose is front-loaded, followed by the parameter behavior and the no-reservation guarantee. No filler and nothing repeated from schema or annotations.

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?

With an output schema present and annotations covering the safety profile, the description only needs purpose, the one non-obvious parameter, and side effects — all of which it provides. Marginally incomplete in that it never frames this against the actual-usage tool get_usage.

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

Parameters4/5

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

Schema description coverage is 0%, so the description carries the burden, and it explains text_chars meaningfully: it only contributes to the estimate when supplied, otherwise that cost is excluded. input_path is left unexplained, but its meaning is self-evident, so coverage is adequate.

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

Purpose4/5

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

States a specific verb and resource ('Estimate cloud cost before transcription'), which is distinct from every sibling (get_usage reports actual usage, caption_video does work). It stops short of naming the tool it contrasts with, so it is clear but not fully sibling-differentiated.

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

Usage Guidelines3/5

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

The description gives a conditional instruction for supplying text_chars ('supply known text_chars for editing/translation, otherwise their cost is excluded'), which is genuinely useful usage context. However, it never says when to call this estimator at all versus alternatives like get_usage or preview_style, so guidance is implied rather than explicit.

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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