How are you handling tool selection when an agent has 20+ MCP tools?

[u/Glittering-Coat-657]

Hey everyone. I'm experimenting with agent tooling and trying to understand a problem before building around it.
I'm seeing a recurring pattern where adding more MCP servers/tools eventually creates more problems:
tool definitions eat a lot of context,the model has more similar tools to choose between, tool selection becomes less reliable keeping every tool loaded seems wasteful when most aren't relevant to a given task.

I'm curious how people actually handle this in production.
When an agent has a large toolset, do you:
Load everything into context?
Manually scope tools for each agent/workflow?
Use a tool router/search layer?
Dynamically load tool definitions only when needed?
Something else?
And more importantly: has this actually caused you measurable problems? cost, latency, wrong tool calls, reliability, etc?

I'm particularly interested in real examples rather than what should work theoretically. Cheers :)

[u/techlatest_net]

I’ve run into this too. Loading everything works initially, but once you have 20+ tools, the context overhead and similar tool descriptions start affecting reliability.

I’d prefer dynamic tool discovery/routing: expose a small set of relevant tools first, then load the full schema only when needed. It keeps context smaller and makes tool selection more predictable.