capture_pane

Python

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Capture the visible contents of a tmux pane (terminal scrollback).

Use for tmux pane output — ‘capture the build log’, ‘what did the server print’ — not editor file contents. The tool for reading what is displayed in a terminal; use search_panes to search across multiple panes at once.

Output is tail-preserved: when the capture exceeds max_lines the oldest lines are dropped and the returned string is prefixed with a single [... truncated K lines ...] header line so the agent can tell truncation occurred and re-request with a narrower start/end window or a larger max_lines if needed. Pass max_lines=None to disable truncation entirely.

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Arguments

end optional: End line number.
Default: null.
max_lines optional: Maximum number of lines to return. Defaults to ``CAPTURE_DEFAULT_MAX_LINES``. Pass ``None`` to return the full capture with no truncation.
Default: 500.
pane_id optional: Pane ID (e.g. '%1').
Default: null.
session_id optional: Session ID (e.g. '$1') for pane resolution.
Default: null.
session_name optional: Session name for pane resolution.
Default: null.
socket_name optional: tmux socket name.
Default: null.
start optional: Start line number. 0 is the first visible line. Negative values reach into scrollback history (e.g. -100 for last 100 lines).
Default: null.
window_id optional: Window ID for pane resolution.
Default: null.

Schemas

The schema defines required fields, nested values, defaults, and validation constraints.

Input schema

{
  "additionalProperties": false,
  "properties": {
    "end": {
      "anyOf": [
        {
          "type": "integer"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "End line number."
    },
    "max_lines": {
      "anyOf": [
        {
          "type": "integer"
        },
        {
          "type": "null"
        }
      ],
      "default": 500,
      "description": "Maximum number of lines to return. Defaults to\n``CAPTURE_DEFAULT_MAX_LINES``. Pass ``None`` to return the\nfull capture with no truncation."
    },
    "pane_id": {
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "Pane ID (e.g. '%1')."
    },
    "session_id": {
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "Session ID (e.g. '$1') for pane resolution."
    },
    "session_name": {
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "Session name for pane resolution."
    },
    "socket_name": {
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "tmux socket name."
    },
    "start": {
      "anyOf": [
        {
          "type": "integer"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "Start line number. 0 is the first visible line. Negative values\nreach into scrollback history (e.g. -100 for last 100 lines)."
    },
    "window_id": {
      "anyOf": [
        {
          "type": "string"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "Window ID for pane resolution."
    }
  },
  "type": "object"
}

Tool annotations

{
  "destructiveHint": true,
  "idempotentHint": false,
  "openWorldHint": true,
  "readOnlyHint": false
}