mcp-context-cost

perplexity — context cost

133 tokens across 1 tools — lean (< 1K). Measured 2026-09-30 under methodology v1.0.

An Anthropic request carries 133 of those tokens as tool definitions, and Claude counts those at 503.

   
server (self-reported) example-servers/perplexity-ask v0.1.0
status measured
tokenizer tiktoken / o200k_base
launch command npx -y server-perplexity-ask
isolation docker · public.ecr.aws/docker/library/node:22-slim · network bridge · linux/amd64 · network enabled for package fetch; clean FS, no host credentials
env vars supplied PERPLEXITY_API_KEY
canonical SHA-256 bf3f548ecca0308f30e544a03d3a36778dbbfba3a5ed12dab6d981dcbcc7a73c
category vendor-official
source https://github.com/perplexityai/modelcontextprotocol

Where the tokens are

tool tokens share description input schema
perplexity_ask 131 98.5% 38 80

Each tool is tokenized on its own, so the parts do not sum exactly to the whole: the array adds its own brackets and commas, and the tokenizer merges tokens across object boundaries. The badge number is always the count of the whole array, never a sum of parts.

What this costs on Claude

Measured 2026-09-14 against claude-opus-5 via Anthropic’s count_tokens (method tools-delta/v1).

  tokens  
o200k, full capture 133 the badge number — every byte tools/list returned
o200k, Anthropic fields only 133 0.0% of the capture is MCP-only metadata
Claude, same fields 503 3.78× the badge number

An Anthropic tool definition carries name, description, and input_schema and nothing else, so title, annotations, outputSchema, execution, and icons are dropped before the request — that is the second row. The third row is the same tools counted by Anthropic, which is larger than the second because Anthropic’s tokenizer is denser on this content than o200k_base and the API adds its own framing (at most 328 tokens of it fixed, measured against a single minimal tool). The two effects run in opposite directions, which is why the Claude number is not a fixed multiple of the badge.

Over time

date tokens tools release measured in change
2026-08-16 133 1 not recorded not recorded —
2026-08-19 133 1 not recorded docker no change
2026-09-04 133 1 0.1.0 docker no change
2026-09-05 133 1 0.1.0 docker no change
2026-09-09 133 1 0.1.0 docker no change
2026-09-30 133 1 0.1.0 docker no change

Some of these sweeps predate the isolation column, so the conditions they were measured under are not on record.

Full series: results/history.csv.

Re-derive it

npx -y mcp-context-cost verify results/perplexity/measurement.json

That re-tokenizes the published capture and checks the count and the hash. If it disagrees with the badge, the badge is wrong — open an issue and it gets corrected.

Badge JSON · All servers · Leaderboard · Methodology