vapi-mcp-server

vapi_update_assistant

Modify an existing Vapi assistant's configuration by providing its ID and the data fields to update.

Instructions

Update an existing Vapi assistant

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": {
      "id": "<id>",
      "data": "<data>"
    },
    "name": "vapi_update_assistant"
  }
}

Input Schema

Name	Required	Description	Default
`id`	Yes
`data`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jun 21, 2026

TDQS

C2.6/5.0

Behavior2/5

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

With no annotations, the description must disclose behavioral traits. It only says 'update', which implies modification, but does not mention whether it performs a partial update or full replace, error behavior for non-existent ids, idempotency, or any side effects. This is insufficient transparency.

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

Conciseness3/5

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

The description is a single short sentence, which is concise but arguably too terse. It states the core function but omits necessary details for a tool with a complex nested parameter. Every word is earned, but not enough information is conveyed.

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?

Given the complexity (nested object, no output schema, no annotations), the description is incomplete. It does not explain how the update works (merge vs replace), the expected structure of 'data', or what the response contains. The tool's purpose is hinted but execution details are missing.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must explain parameters. It does not describe that 'id' is the assistant identifier or that 'data' is an object with arbitrary fields for updating. The description adds no meaning beyond the input schema.

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?

The description states 'Update an existing Vapi assistant', clearly indicating the verb (update) and resource (assistant). This distinguishes it from siblings like vapi_create_assistant, vapi_get_assistant, and vapi_delete_assistant. However, it lacks detail on what aspects can be updated.

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 is provided on when to use this tool versus alternatives like re-creating the assistant. There are no prerequisites mentioned, such as the assistant existing before update, nor exclusions for when not to use this tool.

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