Skip to main content
Glama

heygen_list_voices

Read-onlyIdempotent

Fetch all HeyGen avatar voices using your API key to select the right voice for AI video creation.

Instructions

List all available voices for HeyGen avatar videos.

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": {
      "api_key": "<api_key>"
    },
    "name": "heygen_list_voices"
  }
}

Input Schema

NameRequiredDescriptionDefault
api_keyYesHeyGen API key

Schema Changelog

Changes observed during successful MCP inspections.

  1. Addedv0.1.5

TDQS

A3.6/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered. The description adds only the implicit claim that the list is complete ('all available'), with no mention of auth scope, rate limits, or whether results are paginated or filtered by language/gender.

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?

A single front-loaded sentence with no boilerplate or redundancy; nothing could be trimmed without losing information.

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?

For a one-parameter read-only list tool with full annotation coverage, the description says enough to select and call it correctly. The only gap is that there is no output schema and the description doesn't hint at what a voice record contains (id, name, language), which the agent would need to pick a voice.

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?

Only one parameter (api_key) and schema description coverage is 100%, so the schema fully documents it; the description adds no extra meaning about the key or its scope. Baseline 3 is appropriate when the schema does the work.

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 ('List all available voices') plus scope ('for HeyGen avatar videos'), which distinguishes it by noun from heygen_list_avatars. It does not explicitly name the sibling, so it falls short of a 5.

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 phrase 'for HeyGen avatar videos' implies the use case (fetching a voice before calling heygen_create_avatar_video), but there is no explicit when-to-use or when-not-to-use guidance and no named alternative.

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

Deploy Server

Other Tools