google-flow-mcp

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Download media to disk

flow_download

Idempotent

Resolve a Flow media ID to a signed CDN URL, write the bytes to disk, and verify the file is genuine image or video data. Reliable alternative when Flow's Download button fails.

Instructions

Resolve a Flow media id to its signed CDN url and write the bytes to disk, verifying the file is genuinely image or video data. Use this rather than Flow's Download button, which frequently writes nothing in an automated profile. Never charges.

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": {
      "media_id": "<media_id>",
      "out_file": "<out_file>"
    },
    "name": "flow_download"
  }
}

Input Schema

Name	Required	Description	Default
`media_id`	Yes	Media id from flow_list_media
`out_file`	Yes	Output filename; relative paths resolve under FLOW_OUTPUT_DIR

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 29, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already indicate it's not read-only (readOnlyHint false), not destructive (destructiveHint false), and idempotent (idempotentHint true). The description adds context about writing to disk, verifying file types, and no charges. 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.

Conciseness5/5

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

Two sentences, each serving a distinct purpose: first explains the action, second provides usage guidance. No redundant or filler content. Information is front-loaded.

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 the tool's simplicity (2 parameters, no output schema, rich annotations), the description covers the core behavior, usage recommendation, and important behavioral traits. It feels complete for an AI agent to decide when and how to invoke it.

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 coverage is 100% with descriptions for both parameters. The description adds extra meaning: 'Media id from flow_list_media' for media_id and 'relative paths resolve under FLOW_OUTPUT_DIR' for out_file, providing useful context beyond the schema.

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 tool resolves a media ID to a signed CDN URL and writes bytes to disk, verifying the file type. This specific verb+resource combination distinguishes it from sibling tools like flow_list_media or flow_delete_media.

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

Usage Guidelines4/5

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

The description explicitly recommends using this tool over Flow's Download button due to reliability issues in automated profiles. It also mentions 'Never charges,' providing cost context. While not covering when not to use it, the guidance is clear and helpful.

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