Measuring a catalogue's cost
How many tokens an agent pays merely for having skills installed, and why that bill cannot be read off the skill count.
What you get
- A concrete per-session cost instead of "a lot of skills"
- A grasp that the bill is fixed and paid for skills you never use
- A tool that recomputes it after every change
Why the skill count is not the bill
A catalogue of 260 skills costs 22.3k tokens in every session. That price is not paid for use, it is paid for presence: the host reads the description of every installed skill at session start, whatever you asked for. A skill that has not fired once in six months costs exactly as much as one you need daily.
What a profile buys
Switching to the infra-ops profile leaves 49 skills and drops the bill to 3.2k.
The other 211 are not deleted, they move into .archive - the host does not see
them, the rollback is instant, and nothing is lost.
| State | Skills | Tokens per session |
|---|---|---|
| Full catalogue | 260 | 22.3k |
infra-ops profile |
49 | 3.2k |
web-dev profile |
72 | 5.2k |
Blocked skills
26 of the 260 require a connected MCP server. They cost 3.2k tokens, cannot
run, and - worse - win routing against skills that can. The installer prefixes
their description with [needs MCP: …] so the model routes around them. The
prefix clears itself once the server is connected and the skills reinstalled.
The disconnected side is measured too: npm run mcp-test stands up a local MCP
server, asserts both directions of the transition, and restores the
environment. 22 assertions; a green run means “the platform reacts correctly to
a connected server” - not “the hyperfx skills work”, which needs a real account.