What data does Chron log?
Every exchange records the user message’s received timestamp and the assistant response’s sent timestamp, along with full content and session metadata.
Chron MCP Server
@SirinivasK
Basic information
About Chron MCP Server
AI tools show when you sent a message. Chron logs when the AI responded too — and keeps a permanent, queryable record of every exchange across every tool you use. Works with Claude Desktop, Claude Code, Cursor, Windsurf, and any MCP-compatible AI tool. Every exchange is stored wi
Chron MCP Server config
Add this server to your MCP-compatible client using the configuration below.
{
"mcpServers": {
"chron": {
"command": "npx",
"args": [
"-y",
"chron-mcp"
]
}
}
}Chron MCP Server tools
15Initialize or resume an audit session. Returns session_id, message_count, first_message_at, and recent messages in a single call — use this instead of calling start_session + get_session_history separately.
Create a new audit session or resume an existing one by title. Call this at the start of every conversation.
Record a single message (user or assistant) with the current local datetime and timezone offset. Call before responding for user messages, and before sending for assistant messages.
Record an AI tool invocation as a first-class audit event (event_type=tool_call). Call immediately before executing a tool. Returns tool_call_id to pass to log_tool_result.
Record the result of a tool call as a first-class audit event (event_type=tool_result). Call immediately after receiving tool output. Links back to log_tool_call via tool_call_id.
Record a file edit as a first-class audit event (event_type=code_change). Call after every Edit or Write tool call with the unified diff. Diff content is included in the hash chain.
Record a user+assistant exchange from historical or batch imports only. Do NOT use for live conversations — both timestamps are captured at the same instant with no real gap. For live sessions always call log_message twice: once for the user message, once for the assistant response.
List all audit sessions ordered by most recently active. Returns id, title, ai_tool, message_count, created_at, updated_at.
Retrieve the full timestamped audit log for a session, oldest first.
Verify the tamper-evident hash chain for a session. Returns valid=true if no rows were edited after logging, or the first broken link if tampering is detected.
Scan a prompt for secrets and sensitive data before sending to any AI. Returns detected secrets, a redacted version with tokens, and a token_map to restore the real values after the AI responds.
Permanently delete a session and all its messages. Cascades to secrets_detected. Returns deleted=true or deleted=false if not found.
Full-text search across all logged AI conversations. Returns matching sessions with excerpts. Uses SQLite FTS5 with porter stemming — supports phrases ("exact match"), boolean (term1 OR term2), and prefix (migrat*).
Return a structured summary of a session: timeline with latencies, mutations detected, secrets touched, and possible prod-account references. Useful for compliance review and change-control evidence.
Restore real secret values into an AI response that contains $CHRON_* tokens. Pass the token_map returned by scan_prompt.
Overview
What is Chron?
Chron is an MCP server that provides a timestamped audit trail for every AI conversation. It logs each exchange with precise local datetime (including timezone offset) to a local SQLite file you own. Works with Claude Desktop, Claude Code, Cursor, Windsurf, and any MCP-compatible AI tool.
How to use Chron?
Add the server to your AI tool’s MCP configuration by setting command to npx and args to ["-y", "chron-mcp"]. First run automatically creates ~/.chron/chron.db. For Claude Code, additionally install the companion skill hook to enable automatic session logging. Run as HTTP+SSE for team/self-hosted use by setting CHRON_TRANSPORT=http.
Key features of Chron
- Logs user and assistant timestamps with timezone offset
- Stores audit trail in a local SQLite file you own
- Tamper-evident SHA-256 hash chaining
- Companion skill file for automatic logging
- HTTP+SSE mode for remote/team usage
- Works with any MCP-compatible AI tool
Use cases of Chron
- Audit AI conversation timestamps and response generation time
- Retrieve full conversation history with exact timing across sessions
- Verify message integrity after logging via hash chain verification
- Self-host a shared audit trail for a team’s AI interactions
- Query your entire conversation log directly with SQLite tools
Frequently asked questions
Where is my data stored?
Your audit log lives in a single SQLite file at `~/.chron/chron.db` (configurable via `CHRON_DB_PATH`). No data leaves your machine; no cloud or telemetry.
How does tamper-evident hashing work?
Each message is linked to the previous one via a SHA-256 chain. The `verify_session` tool walks the chain and reports whether any message has been modified post-logging and the exact row of the first break.
Which AI tools does Chron support?
Claude Desktop, Claude Code, Cursor, Windsurf, and any MCP-compatible AI tool. Installation instructions are provided for each.
Do I need an API key for normal use?
No. In stdio mode (default) no API key is required. An API key is optional and only needed when using HTTP+SSE mode.
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