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The Captcha MCP server costs 351 tokens before the first call.

Connect Captcha and its 3 tool definitions are loaded into the model's context on every request — 0.2% of a 200k window spent before your agent does anything.

QUICK ANSWER The Captcha MCP server's tool definitions consume 351 tokens — below the median MCP server (1,905 tokens). A scoped grant exposing only the tools you use cuts that roughly in proportion.

MEASURED FROM SCHEMAS 3 tools · 351 tokens · 0.2% of 200k · 0.0% of 1M Method →

What that buys before your agent starts working.

Tool definitions are overhead: they occupy context on every request and compete with your code, documents and conversation history for the same window.

200K WINDOW 0.2%
1M WINDOW 0.0%

Corpus context: Captcha ranks #3004 of 3,213 measured MCP servers by definition cost. The median is 1,905 tokens, p90 is 7,952, and the heaviest (Fusionauth) is 183,337 — 92% of a 200k window on its own.

Where the 351 tokens go.

Each row is one tool definition as a tools/list entry — name, description and input schema — counted with o200k_base. Average: 117 tokens per tool.

ToolCategoryTokens% of server
verify Read 193 55.0%
challenge Read 83 23.6%
status Read 75 21.4%

Most agents use a handful of these tools. They pay for all 3.

A PolicyLayer grant exposes only the tools you allow — ungranted definitions are filtered out of the tool list, so they never enter the context window. Estimates below assume typical-weight tools (117 tokens each).

At 3 tools, Captcha is already a small surface — the win here is policy control and audit rather than token savings.

Captcha token-cost questions.

How many tokens does the Captcha MCP server use?+

Its 3 tool definitions total 351 tokens — 0.2% of a 200k context window — measured with tiktoken o200k_base over the serialised tools/list payload. Exact counts vary slightly by client and model.

Why does Captcha consume tokens before I send a message?+

MCP clients load every connected server's tool definitions — name, description, and input schema — into the model's context so it knows what it can call. That payload is charged against your context window on every request, whether or not a tool is used.

How do I reduce Captcha's token usage?+

Expose fewer tools. A PolicyLayer grant scopes Captcha to only the tools you allow — ungranted definitions are filtered out of the tool list, so they never enter the context window.

Does deferred tool loading fix this?+

Partially, in some clients. Claude Code defers MCP tool schemas behind a tool-search step by default, and VS Code has experimental grouping — but you still pay tokens per search and reload, and Cursor, Windsurf and Gemini CLI load definitions upfront. Reducing the exposed tool set cuts the cost in every client.

How these numbers were measured.

01
Serialisation

Each tool is serialised as a tools/list entry — name, description, input schema — from the schemas in the PolicyLayer scan database. Clients differ slightly in framing, so treat counts as close estimates.

02
Tokeniser

tiktoken o200k_base (GPT-4o/o-series). Anthropic's current tokeniser isn't published, so Claude's exact counts will differ; for English text and JSON schemas the totals are close enough to treat these as estimates.

03
Deferred loading

Some clients now defer schema loading (Claude Code's tool search; VS Code experimental grouping). You still pay per search and reload — and Cursor, Windsurf and Gemini CLI load everything upfront.

Computed 07-06-2026 from the PolicyLayer scan database over all 3 catalogued Captcha tools. Counts refresh with every site build.

Expose only the tools you use — the rest never enter your context.

A PolicyLayer grant scopes Captcha to the tools you actually allow. Ungranted definitions never load, and every call that does run is checked against policy first.

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4,600+ MCP servers and 31,000+ tools scanned and risk-classified.

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