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spix_playbook_voice_list

List available voices for phone calls and emails, with optional language filter to select the appropriate voice for your communications.

Instructions

List available voices

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
languageNoFilter by language code

Implementation Reference

  • Schema definition for the 'playbook.voice.list' command. Sets the path, CLI usage, HTTP method (GET), API endpoint (/playbooks/voices), and parameters (optional 'language' filter). This is the source-of-truth entry that generates the MCP tool 'spix_playbook_voice_list'.
    CommandSchema(
        path="playbook.voice.list",
        cli_usage="spix playbook voice list [--language <code>]",
        http_method="GET",
        api_endpoint="/playbooks/voices",
        mcp_expose="tool",
        mcp_profile="safe",
        description="List available voices",
        params=[
            CommandParam("language", "string", description="Filter by language code"),
        ],
    ),
  • Registration: The MCP tool name 'spix_playbook_voice_list' is generated here by converting 'playbook.voice.list' to 'spix_playbook_voice_list' (line 90). The tool is registered with the MCP server via the Tool() object using the schema from registry.py.
    for schema in tool_schemas:
        # Convert path to tool name: playbook.create -> spix_playbook_create
        tool_name = f"spix_{schema.path.replace('.', '_')}"
        tool_defs.append(
            Tool(
                name=tool_name,
                description=schema.description or f"Spix {schema.path}",
                inputSchema=build_json_schema(schema),
            )
        )
  • Handler: The generic create_tool_handler function handles all tool calls including spix_playbook_voice_list. It resolves the tool name to its schema (playbook.voice.list -> GET /playbooks/voices), validates session scope, and dispatches the GET request to the backend API.
    async def create_tool_handler(
        session: McpSessionContext,
        tool_name: str,
        arguments: dict,
    ) -> list:
        """Execute an MCP tool call by dispatching to the backend API.
    
        This function:
        1. Resolves the tool name to a command schema
        2. Validates session scope (playbook access, channel access)
        3. Builds the API request
        4. Dispatches to the backend
        5. Returns the response as MCP TextContent
    
        Args:
            session: The MCP session context for scope validation.
            tool_name: The MCP tool name (e.g., "spix_playbook_create").
            arguments: The tool arguments from the MCP client.
    
        Returns:
            List containing a single TextContent with the JSON response.
        """
        # Import here to avoid circular imports and handle missing mcp package
        try:
            from mcp.types import TextContent
        except ImportError:
            # Fallback for when mcp is not installed
            class TextContent:  # type: ignore[no-redef]
                def __init__(self, type: str, text: str) -> None:
                    self.type = type
                    self.text = text
    
        # Resolve tool name to schema
        schema = get_schema_by_tool_name(tool_name)
        if not schema:
            return [
                TextContent(
                    type="text",
                    text=orjson.dumps(
                        {"ok": False, "error": {"code": "unknown_tool", "message": f"Unknown tool: {tool_name}"}}
                    ).decode(),
                )
            ]
    
        # Validate tool access (not disabled)
        try:
            session.validate_tool_access(schema.path)
        except Exception as e:
            from spix_mcp.session import McpScopeError
    
            if isinstance(e, McpScopeError):
                return [TextContent(type="text", text=orjson.dumps({"ok": False, "error": e.to_dict()}).decode())]
            raise
    
        # Validate channel access if applicable
        channel = infer_channel_from_tool(schema.path)
        if channel:
            try:
                session.validate_channel_access(channel)
            except Exception as e:
                from spix_mcp.session import McpScopeError
    
                if isinstance(e, McpScopeError):
                    return [TextContent(type="text", text=orjson.dumps({"ok": False, "error": e.to_dict()}).decode())]
                raise
    
        # Handle playbook_id: validate and apply default
        playbook_id = arguments.get("playbook_id")
        try:
            effective_playbook = session.validate_playbook_access(playbook_id)
            if effective_playbook and not playbook_id:
                # Apply default playbook
                arguments["playbook_id"] = effective_playbook
        except Exception as e:
            from spix_mcp.session import McpScopeError
    
            if isinstance(e, McpScopeError):
                return [TextContent(type="text", text=orjson.dumps({"ok": False, "error": e.to_dict()}).decode())]
            raise
    
        # Build endpoint URL with path parameters
        endpoint, remaining_args = build_endpoint_url(schema, arguments)
    
        # Dispatch to backend API
        client = session.client
        method = schema.http_method.lower()
    
        if method == "get":
            response = await asyncio.to_thread(client.get, endpoint, params=remaining_args if remaining_args else None)
        elif method == "post":
            response = await asyncio.to_thread(client.post, endpoint, json=remaining_args if remaining_args else None)
        elif method == "patch":
            response = await asyncio.to_thread(client.patch, endpoint, json=remaining_args if remaining_args else None)
        elif method == "delete":
            response = await asyncio.to_thread(client.delete, endpoint, params=remaining_args if remaining_args else None)
        else:
            response = await asyncio.to_thread(client.get, endpoint)
    
        # Build response envelope
        envelope: dict = {"ok": response.ok, "meta": response.meta}
        if response.ok:
            envelope["data"] = response.data
            if response.pagination:
                envelope["pagination"] = response.pagination
            if response.warnings:
                envelope["warnings"] = response.warnings
        else:
            envelope["error"] = response.error
    
        return [TextContent(type="text", text=orjson.dumps(envelope).decode())]
  • Helper that resolves the MCP tool name 'spix_playbook_voice_list' to its CommandSchema by stripping 'spix_' prefix and converting underscores back to dots, matching against the registry.
    def get_schema_by_tool_name(tool_name: str) -> CommandSchema | None:
        """Look up a CommandSchema by MCP tool name.
    
        MCP tool names follow the pattern: spix_{path with dots replaced by underscores}
        e.g., "spix_playbook_create" -> "playbook.create"
    
        Args:
            tool_name: The MCP tool name (e.g., "spix_playbook_create").
    
        Returns:
            The matching CommandSchema, or None if not found.
        """
        # Remove the spix_ prefix
        if not tool_name.startswith("spix_"):
            return None
    
        path_part = tool_name[len("spix_") :]
    
        # Convert underscores back to dots for path lookup
        # We need to handle multi-part paths like "billing_credits_history" -> "billing.credits.history"
        # Try different dot positions to find the right one
        for cmd in COMMAND_REGISTRY:
            # Convert the command path to expected tool name format
            expected_tool = cmd.path.replace(".", "_")
            if expected_tool == path_part:
                return cmd
    
        return None
Behavior2/5

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

No annotations provided; description only states the action without disclosing any behavioral traits such as read-only nature, authentication requirements, or return format. The full burden falls on the description, which remains minimal.

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?

Extremely concise single sentence that is front-loaded with the action. Every word earns its place with no redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite simplicity, the description lacks details such as what information the list returns (e.g., names, IDs), how the language filter works, or whether pagination exists. For a list tool, more context would be beneficial.

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% (the only parameter 'language' is described). The tool description adds no extra meaning beyond the schema, achieving the baseline.

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?

Description clearly states verb 'List' and resource 'voices', providing a straightforward purpose. However, it does not differentiate from sibling tools like spix_playbook_list or spix_playbook_language_list, lacking context on what 'voices' refers to in this domain.

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

Usage Guidelines2/5

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

No guidance on when to use this tool versus alternatives. With many sibling list tools, agents have no information on when 'list available voices' is appropriate.

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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