Too Many MCP Tools Make the Assistant Worse
Stacking MCP servers makes the assistant slower and worse at picking the right tool, because every tool schema is stuffed into the prompt before you type. Anthropic measured a five-server setup at 58 tools and about 55,000 tokens before the conversation starts. Google Autocomplete already completes too many mcp tools, cursor mcp too many tools, and github mcp too many tools. Reddit’s r/mcp repeats the same war story: past a few dozen active tools, selection falls apart.
This is not “buy more context.” It is a design limit. The fix is fewer tools in view, or tools loaded only when asked for.
What Anthropic actually measured
In Introducing advanced tool use, Anthropic lists a realistic MCP pile:
| Server | Tools | Approx. tokens |
|---|---|---|
| GitHub | 35 | ~26,000 |
| Slack | 11 | ~21,000 |
| Sentry | 5 | ~3,000 |
| Grafana | 5 | ~3,000 |
| Splunk | 2 | ~2,000 |
| Total | 58 | ~55,000 |
Their Tool Search Tool keeps only a search helper up front (~500 tokens), then loads 3–5 relevant tools (~3K). They report context dropping to about 8.7K tokens (about 85% less) and MCP-eval accuracy rising: Opus 4 from 49% to 74%, Opus 4.5 from 79.5% to 88.1%.
Claude’s developer docs say the same in plainer language: Tool search tool. Ability to pick the right tool degrades once you exceed 30–50 available tools. Use tool search when you have 10 or more tools, definitions over 10k tokens, or you aggregate multiple MCP servers.
A GitHub issue on the MCP spec (#2808) measured 5–15× more tokens than a minimal schema, and ~1,000 tokens for a single heavy tool. That is why “just add the GitHub server” feels free and is not.
On r/mcp, operators describe 58 servers and 680 tools and then *hiding* most of them so each model call stays under ~30 tools. The instinct is correct even if the stack is oversized.
What to do this week
| Symptom | Do this |
|---|---|
| Claude/Cursor calls the wrong tool | Turn servers off until you have a handful that match the job |
| First message is slow or the context meter is already fat | You are paying the schema tax. Prune. |
| GitHub MCP “has everything” and does nothing well | Official servers have been cut back after growing past 100 tools. Prefer a smaller surface. |
| The team each added a different pile | One approved catalog, admins turn tools off. Manage MCP for a team |
Do not keep a global mcp.json with twelve npx servers “just in case.” Do keep one hosted catalog and disable what you do not run this month.
ToolRouter is that catalog: connect once, admin toggles, spend caps. Skills-aware hosts can list operation guides on demand (Skills over MCP) instead of injecting the whole menu. Hosts that cannot still work; you just have to keep the enabled set small.
Cursor: project .cursor/mcp.json so the marketing repo does not load the infra servers. How to add MCP to Cursor.
Claude Code may already defer schemas when tool search is on. Consumer Claude chat still sees whatever you enabled in that conversation. Enable the connector for the chat, not every connector you ever added.
Give your AI superpowers. Copy one instruction and paste it into your AI.
Skills vs fewer MCP servers
Skills are not a magic shrink ray for a 200-tool GitHub server. They are instructions. If the problem is *access*, keep MCP but cut the list. If the problem is *how we do the job*, add a skill. Claude Skills vs MCP.
When ToolRouter is not the answer
- You already run Claude’s Tool Search Tool on the API and like it. Keep it.
- You only needed filesystem plus one database. Two local servers can be the whole setup.
- You wanted a security review of random npm MCP packages. Start with Shadow MCP, then prune.
Connect ToolRouter, turn off what you do not use, and stop installing a new server for every blog post you read.
Frequently Asked Questions
How many MCP tools is too many?
**Anthropic’s docs flag 30–50 visible tools as the range where selection accuracy drops.** There is no magic number. Wrong-tool calls and a fat first message are the tells.
Does Cursor have the same problem?
**Yes if every schema is loaded.** Cursor has been moving toward on-demand discovery. Autocomplete still offers `cursor mcp too many tools`. Keep the project list short anyway.
Will one ToolRouter connection dump 200 tools into Claude?
**The catalog is large. What the host loads depends on the client.** Turn unused tools off in the team admin, enable the connector only in the chats that need it, and prefer hosts that search tools instead of injecting all of them.
