Heroku MCP Tool Search Server MCP Server

MCP Tool Search Server

The Problem: When you give Claude 50+ tools, two things break:

1. Context bloat - Tool definitions eat 10-20K tokens, leaving less room for actual work
2. Selection accuracy - Claude gets confused and picks wrong tools when there are too many

The Solution: Instead of loading all tools upfront, Claude searches for tools and loads only what it needs.

Without Tool Search:              With Tool Search:
┌─────────────────────┐           ┌─────────────────────┐
│ Load 100 tools      │           │ Load 1 search tool  │
│ (20K tokens)        │           │ (200 tokens)        │
│                     │           │                     │
│ Claude picks wrong  │           │ Claude searches:    │
│ tool 30% of time    │           │ "weather" → 2 tools │
│                     │           │                     │
│ Context nearly full │           │ 95% context free    │
└─────────────────────┘           └─────────────────────┘

How It Works

1. You register your tools with this server (via REST API)
2. Claude gets access to search tools (tool_search_bm25, tool_search_semantic, tool_search_regex)
3. When Claude needs a tool, it searches → gets back tool names → uses them

Three search methods:

• BM25 - Keyword matching ("weather" finds get_weather, get_forecast)
• Semantic - Meaning-based ("send a message" finds send_email)
• Regex - Pattern matching (get_.* finds all getter tools)

Deploy to Heroku

Or manually:

heroku create my-tool-search
heroku buildpacks:set heroku/python
git push heroku main
heroku ai:models:create claude-4-sonnet --as INFERENCE

Register Your Tools

curl -X POST https://your-app.herokuapp.com/tools \
  -H "Content-Type: application/json" \
  -d '{
    "name": "get_weather",
    "description": "Get current weather for a location",
    "input_schema": {
      "type": "object",
      "properties": {"location": {"type": "string"}},
      "required": ["location"]
    }
  }'

Test It

export INFERENCE_KEY=$(heroku config:get INFERENCE_KEY -a my-tool-search)
export INFERENCE_URL=$(heroku config:get INFERENCE_URL -a my-tool-search)

curl -s "$INFERENCE_URL/v1/agents/heroku" \
  -H "Authorization: Bearer $INFERENCE_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-4-sonnet",
    "messages": [{"role": "user", "content": "Find tools for checking weather"}],
    "tools": [{"type": "mcp", "name": "mcp-tool-search/tool_search_semantic"}]
  }'

API Reference

MCP Tools