Send a follow-up message to the dealer continuing the conversation. Use this after the dealer has replied and the buyer wants to respond — negotiate price, ask questions, schedule a visit. The email thread continues naturally.
| Name | Required | Description | Default |
|---|---|---|---|
| vin | Yes | VIN of the vehicle being discussed | |
| message | Yes | The follow-up message to send to the dealer | |
| session | Yes | Session hash | |
| agent_id | No | Your agent identifier |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of behavioral disclosure. It adds useful context that the email thread continues naturally and prerequisites (after dealer reply), but it does not discuss side effects, irreversibility, or failure modes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences, front-loaded with the action ('Send a follow-up message') and followed by concise usage guidance. No wasted words.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple message-sending tool with no output schema, the description adequately covers what it does and when to use it. It could mention application state requirements more explicitly, but given the schema richness, it is sufficient.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The input schema already describes all four parameters (vin, message, session, agent_id) with 100% coverage, so the description adds no additional parameter semantics beyond what the schema provides.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool sends a follow-up message to the dealer, with specific use cases (negotiate, ask questions, schedule visit). It distinguishes itself from sibling tools by emphasizing 'follow-up' and 'continuing the conversation.'
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly says to use this after the dealer has replied and the buyer wants to respond, providing clear timing. However, it does not explicitly name alternative tools or state when not to use it, though the 'follow-up' language implies it is not for initial messages.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Most tools target distinct resources (dealer inventory, vehicle search, session actions), but cars_session_message and cars_session_reply have overlapping purposes as both involve posting messages. The session tools are otherwise clearly differentiated by their action verbs.
All tools share the 'cars_' prefix and use snake_case, but the verb-noun pattern is inconsistent: some are action-first (cars_search, cars_session_create) while others are noun-only (cars_vehicle, cars_dealers, cars_history). Session tools follow a consistent 'session_<verb>' structure, but the broader set mixes conventions.
With 19 tools, the set is on the heavy end, falling in the 16-25 range that feels borderline. The count is justified by the comprehensive session workflow, but it approaches the threshold where tool selection becomes cumbersome.
The core journey of searching, inspecting, and tracking vehicles through sessions is well covered, including dealer communication and trade-in. However, there are notable gaps: no way to remove a vehicle from a session or update general buyer profile details (payment method, timeline) after initial creation.