Skip to main content
Glama

Siren

by ai.mysiren
OverviewDiscussionsAdmin

studio_start

Start a video in Siren Studio from a description. Siren composes the first take (about 10 to 20 seconds) and replies with what it made; nothing is rendered or charged until studio_export. Returns the thread and Siren's reply. The human sees the same thread in Studio and can keep editing it there, or you can with studio_edit.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
promptYesWhat to make, in plain words: "an App Store preview for our timer app, calm, show the station picker first". An App Store link works too.
surfaceNoOptional shape: story-reel (9:16), square-ig, wide-desktop (16:9).
templateNoOptional film id to start from (list_films names them). Omit and the director picks.
attachmentsNoOptional files Siren reads and uses: URLs from upload_media (app screenshots, a logo, a reference picture, a short screen recording). Up to 6.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • addedInput schema / properties / attachments
      Added value: +{
+  "anyOf": [
+    {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Optional files Siren reads and uses: URLs from upload_media (app screenshots, a logo, a reference picture, a short screen recording). Up to 6."
+}
  2. Added

TDQS

A4.4/5.0
Behavior5/5

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

Adds substantial context beyond the annotations: no rendering or billing occurs until studio_export (cost side-effect timing), the first take is roughly 10-20 seconds, the returned thread is shared and human-visible, and edits may come from either side. That is exactly the operational detail openWorldHint/destructiveHint cannot convey.

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

Conciseness4/5

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

Front-loaded with the action and its output, then the billing constraint. Four sentences, each carrying distinct information, though the closing sentence about the human-shared thread is slightly wordier than needed.

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 exists, the description needn't enumerate return fields, yet it still names what comes back (the thread and Siren's reply). Combined with the cost/render disclosure and sibling routing, nothing an agent needs to invoke this correctly is missing.

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?

Schema description coverage is 100%, so prompt, surface, template and attachments are already documented with examples in the schema. The description contributes only the framing 'from a description' and does not restate or extend any parameter. Baseline 3 is appropriate.

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?

States a specific verb+resource ('Start a video in Siren Studio from a description') and immediately scopes the outcome ('composes the first take (about 10 to 20 seconds) and replies with what it made'). An agent can distinguish it from studio_edit and studio_export without opening either schema.

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?

Names the alternative tools and the conditions that select them: nothing is rendered or charged until studio_export, and further changes go through studio_edit. Clear workflow context, though it never states when this tool should NOT be used (e.g. reusing an existing thread via studio_threads/studio_get).

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

All Siren toolsInspect
Try in Browser
One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources