mcp-server-claude-chat
An MCP (Model Context Protocol) server for the Anthropic Claude Messages API. Built in Rust, it exposes chat, vision, live web search, and model listing as MCP tools — so any MCP client (Claude Desktop, Claude Code, etc.) can consult Claude as a tool.
Communicates via stdio using JSON-RPC 2.0, like all the other MCP servers in this collection. Structurally it mirrors mcp-server-grok-chat / mcp-server-gpt-chat, adapted to Anthropic's API shape.
Subscription vs. API credits
This server uses the Anthropic API with an API key (API credits). That is the only supported, terms-compliant way to drive Claude from a third-party tool.
A Claude Pro/Max subscription (the kind that powers Claude Code and the Claude apps) is not usable here: that authentication is licensed for Anthropic's own first-party clients, and routing it through a custom server would violate Anthropic's Consumer Terms — the "$200 of Claude usage from another service" concern you raised. So: API key it is. (If you run an Anthropic-compatible gateway, point base_url at it — see Configuration.)
Tools
| Tool | Description |
|---|---|
chat | Send a message to Claude. Supports multi-turn history, a system prompt, model selection, and extended thinking via thinking_budget. |
chat_with_vision | Analyse an image given an image URL and a text prompt. |
chat_with_search | Chat with live web search — Claude searches server-side and answers with cited sources. |
list_models | List available Claude models and their IDs (cached for 5 minutes). |
Note: Anthropic has no embeddings endpoint (they recommend Voyage AI), so unlike the grok/gpt servers there is no
embeddingtool.
chat
| Name | Type | Required | Description |
|---|---|---|---|
prompt | string | yes | The user message to send |
system_prompt | string | no | System prompt to set context/behaviour |
messages | string | no | Conversation history as a JSON array of {role, content} objects (roles: user/assistant only — use system_prompt for system instructions) |
model | string | no | Model ID (default: server default, claude-opus-4-8). Call list_models. |
temperature | float | no | Sampling temperature (0.0–1.0). Ignored when thinking_budget is set. |
max_tokens | integer | no | Max tokens to generate (defaults to the server default) |
thinking_budget | integer | no | Enable extended thinking with this token budget (min 1024). Reasoning is returned in a [thinking] block; max_tokens is auto-raised above the budget. |
chat_with_vision
| Name | Type | Required | Description |
|---|---|---|---|
prompt | string | yes | Text prompt describing what to analyse |
image_url | string | yes | URL of the image (must be http:// or https://) |
model | string | no | Vision-capable model ID (default: server default) |
temperature | float | no | Sampling temperature (0.0–1.0) |
max_tokens | integer | no | Max tokens to generate |
chat_with_search
| Name | Type | Required | Description |
|---|---|---|---|
prompt | string | yes | The user message |
system_prompt | string | no | System prompt |
model | string | no | Model ID (default: server default) |
temperature | float | no | Sampling temperature (0.0–1.0) |
max_tokens | integer | no | Max tokens to generate |
max_uses | integer | no | Max web searches Claude may run for this request (default: 5) |
Web search is billed by Anthropic at $10 per 1,000 searches on top of token costs, and an org admin must enable web search in the Claude Console.
list_models
No parameters. Results cached for 5 minutes.
Prerequisites
- Rust (edition 2024)
- An Anthropic API key from console.anthropic.com
Setup
mkdir -p ~/.config/mcp-server-claude-chat
cp config.toml.example ~/.config/mcp-server-claude-chat/config.toml
# then edit it and set api_key
Config (~/.config/mcp-server-claude-chat/config.toml):
api_key = "sk-ant-..."
# Optional:
# base_url = "https://api.anthropic.com/v1" # or a compatible gateway
# default_model = "claude-opus-4-8"
# default_max_tokens = 4096
The server fails fast at startup if the config is missing or api_key is empty.
Build
cargo build --release # produces target/release/claude-chat
cargo build # debug build
cargo run # run in dev mode
RUST_LOG=debug cargo run
cargo test # unit tests (response formatting, validation, message building)
MCP Configuration
Claude Desktop (~/.config/Claude/claude_desktop_config.json) or any MCP client:
{
"mcpServers": {
"claude-chat": {
"command": "/media/codechap/4TB/develop/mcps/mcp-server-claude-chat/target/release/claude-chat"
}
}
}
Claude Code:
claude mcp add claude-chat -- /media/codechap/4TB/develop/mcps/mcp-server-claude-chat/target/release/claude-chat
Project Structure
src/
main.rs - entry point, config loading, stdio transport setup
server.rs - MCP tool definitions (chat, chat_with_vision, chat_with_search, list_models)
api.rs - Anthropic HTTP client, Messages/Models types, response formatter
params.rs - tool parameter types with serde + JSON Schema derives
config.rs - TOML config loading
License
MIT