CtxWindow
GitHub
updates automatically as you work

Watch your agent's context window fill up as you work.

Every token that entered the model, in the order it loaded: system prompt, tool specs, injected reminders, tool results. Not a summary, the real breakdown, against real cost, over a real MCP connection. No rewritten agent loop, no wrapper.

sess_8f2a1c4e · claude-sonnet-5 · 2m ago
system tools reasoning tool call tool result answer
Tokens
0
Cache hit
0%
Cost
$0.00
Context used
0%
Works with Claude Code claude.ai Bedrock agents GitHub Copilot

What this gives your agent

  • Real per-session cost, token, and tool-call metrics: 8 MCP tools, 7 read-only
  • The Context Window Explorer: exactly what entered the model's context window, block by block, with honest token estimates
  • Your own data, isolated from anyone else connected to this server. Sign in below and everything you record or query is scoped to your account

What CtxWindow stores, and what it never sees

Sign-in mints a bearer token tied to your Google account; CtxWindow never sees your Google password. Session metrics (tokens, cost, tool names) are stored by default. Full prompt/response content is only captured if you turn on the optional raw-body flag, and even then it passes through basic redaction before storage. Your data is never visible to another signed-in user, only to you and the server owner.

What is an MCP server?

MCP (Model Context Protocol) is an open standard that lets an LLM or agent call tools over a normal HTTP connection. This server exposes read/write tools for agent execution data, and is built to support two integration paths: Bedrock-based agents calling the record_session tool directly, and Claude Code.

Why sign in with Google instead of a password?

No account to create or password to remember here. Google verifies who you are, this server just checks the signed proof and hands you a token scoped to your account. That token, not your Google identity itself, is what your agent actually uses afterward.

What does "your own data" actually mean?

Every session recorded through your token is tagged with your account. Reads are filtered the same way, you only ever see, list, or query sessions you recorded. Even guessing another person's session ID reads back as "not found," identical to one that never existed.

Sign in to get your token

One click, no password, no account to create here.