mcp-context-cost

chrome-devtools — context cost

5,717 tokens across 29 tools — moderate (5–15K). Measured 2026-09-04 under methodology v1.0.

An Anthropic request carries 5,100 of those tokens as tool definitions, and Claude counts those at 9,215.

   
server (self-reported) chrome_devtools v1.8.0
status measured
tokenizer tiktoken / o200k_base
launch command npx -y chrome-devtools-mcp
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 none
canonical SHA-256 151a59215c20049ea5934809670996c1d73977d468a65fa6b5624c2e24ca3ef4
category vendor-official
source https://github.com/ChromeDevTools/chrome-devtools-mcp

Where the tokens are

tool tokens share description input schema
emulate 418 7.3% 9 377
list_console_messages 333 5.8% 13 287
evaluate_script 320 5.6% 27 261
take_screenshot 278 4.9% 9 236
list_network_requests 277 4.8% 14 231
navigate_page 266 4.7% 21 214
fill_form 265 4.6% 68 166
performance_start_trace 249 4.4% 35 182
get_network_request 215 3.8% 24 159
take_snapshot 211 3.7% 62 116
new_page 205 3.6% 17 157
lighthouse_audit 197 3.4% 30 132
upload_file 197 3.4% 8 158
press_key 190 3.3% 34 124
performance_analyze_insight 188 3.3% 24 130
fill 186 3.3% 19 137
wait_for 161 2.8% 12 118
click 156 2.7% 5 120
drag 154 2.7% 6 117
performance_stop_trace 143 2.5% 11 100
handle_dialog 141 2.5% 13 96
take_heapsnapshot 137 2.4% 24 80
type_text 137 2.4% 9 96
hover 135 2.4% 5 99
get_console_message 131 2.3% 19 79
select_page 125 2.2% 11 83
resize_page 124 2.2% 13 78
close_page 106 1.9% 16 59
list_pages 70 1.2% 10 29

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 5,717 the badge number — every byte tools/list returned
o200k, Anthropic fields only 5,100 10.8% of the capture is MCP-only metadata
Claude, same fields 9,215 1.61× 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
2026-09-03 5,717 29 not recorded docker —
2026-09-04 5,717 29 1.8.0 docker no change

Full series: results/history.csv.

Re-derive it

npx -y mcp-context-cost verify results/chrome-devtools/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