@tailormade/seq-mcp

MCP server for Seq structured logging — search, query, signals, live events.

Stack

• TypeScript, Node.js >= 20
• @modelcontextprotocol/sdk ^1.5.0
• Zod ^4.3.6

Setup

npm install @tailormade/seq-mcp

Set environment variables:

SEQ_SERVER_URL=https://your-seq-server
SEQ_API_KEY=your-api-key

Claude Desktop / MCP config

{
  "mcpServers": {
    "seq": {
      "command": "node",
      "args": ["node_modules/@tailormade/seq-mcp/dist/index.js"],
      "env": {
        "SEQ_SERVER_URL": "https://your-seq-server",
        "SEQ_API_KEY": "your-api-key"
      }
    }
  }
}

API Key Permissions

The API key needs specific Seq permissions depending on which tools you want to use:

| Permission | Tools | |------------|-------| | Read | All tools |

Minimum required: Read.

Tools

| Tool | Description | Default format | |------|-------------|---------------| | seq_search | Search events by filter, signal, date range | compact | | seq_get_event | Get single event by ID with full details | detail | | seq_recent | Fetch most recent events, supports polling with afterId | compact | | seq_stream | Long-poll for new events (real-time monitoring) | compact | | seq_signals | List all shared signals (cached 10 min) | table | | seq_query | Execute SQL queries (select ... from stream) | table | | seq_expression_indexes | List expression indexes | table | | seq_fields | Discover fields by sampling events (cached 10 min) | - | | seq_query_help | Inline filter + SQL reference docs | - | | seq_prefs | Show current preferences | - | | seq_prefs_update | Update a preference | - | | seq_history | Show cached query history and discovered systems | - | | seq_history_clear | Clear history cache (all, queries, systems, or specific) | - |

Output Formats

All event tools support a format parameter: compact, table, detail, raw.

Default format is configurable via seq_prefs_update key=defaultFormat value=compact.

Preferences

Stored in ~/.seq-mcp-prefs.json:

| Key | Default | Description | |-----|---------|-------------| | defaultFormat | compact | Default output format for event tools | | maxMessageLength | 120 | Truncate messages in compact/table mode | | hideFields | ProcessId,ThreadId,EventId | Fields hidden in detail view | | historyQueryKeepDays | 60 | Auto-prune query history older than N days | | historySystemKeepDays | 60 | Auto-prune system entries older than N days | | maxHistoryQueries | 500 | Max query entries to keep in history |

Architecture

src/
├── index.ts              Entry point — MCP server + tool registration
├── api/
│   ├── client.ts         SeqClient — HTTP calls + caching
│   ├── formatter.ts      Event/signal formatting (compact/table/detail/raw)
│   ├── prefs.ts          Preferences (~/.seq-mcp-prefs.json)
│   └── history.ts        History cache (~/.seq-mcp-history-{hostname}.json)
└── tools/
    ├── search.ts          seq_search, seq_get_event
    ├── signals.ts         seq_signals
    ├── recent.ts          seq_recent
    ├── stream.ts          seq_stream
    ├── query.ts           seq_query, seq_query_help, seq_expression_indexes, seq_fields
    ├── prefs.ts           seq_prefs, seq_prefs_update
    └── history.ts         seq_history, seq_history_clear

References

• Seq HTTP API — Datalust
• Seq SQL query syntax — Datalust
• seq-api C# client — Datalust (reference for endpoint behavior)
• MCP specification — Anthropic

Known limitations

• afterId on /api/events/scan scans backwards, not forward — use seq_recent for forward polling
• seq_stream with very short wait + non-matching filter can cause fetch timeout
• SQL distinct() over full stream may timeout — always set rangeStartUtc
• seq_fields discovers fields by sampling — fields that appear rarely may be missed with small sample sizes
• Properties format varies between Seq versions (array vs object) — formatter handles both