# capture_since

Source: https://libtmux.org/en/py/stable/mcp/tools/capture_since/

> Capture new tmux terminal scrollback since the previous cursor.

tool MCPstable

MCP is in development

Server behavior and tool contracts may change. Tool availability depends on the server configuration.

* **capture_since**( [cursor](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fcursor)?: [string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [max_bytes](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fmax_bytes)?: [integer](https://json-schema.org/understanding-json-schema/reference/numeric "numeric (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [max_lines](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fmax_lines)?: [integer](https://json-schema.org/understanding-json-schema/reference/numeric "numeric (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [pane_id](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fpane_id)?: [string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [session_id](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fsession_id)?: [string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [session_name](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fsession_name)?: [string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [socket_name](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fsocket_name)?: [string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), [window_id](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fwindow_id)?: [string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"), )

  tool \[[source](https://github.com/tmux-python/libtmux-mcp/blob/4daddc0dfca96c43bf521d818bf91564e1434760/src/libtmux_mcp/tools/pane_tools/__init__.py#L106)][¶](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since)

  Capture new tmux terminal scrollback since the previous cursor.

  Use for observation-first workflows: tailing a shell, watching a long-running command, or repeatedly checking a tmux workspace pane without re-sending the same visible screen every turn. The first call with `cursor=None` returns the current visible pane and an opaque cursor. Later calls pass that cursor back and receive only rows written or rewritten after the cursor, as long as tmux still retains the required scrollback history.

  If tmux history was cleared or trimmed before the cursor anchor, the tool returns the current visible pane with `lines_missed=True` and a fresh cursor. Malformed cursors, cursors for a different pane, pane death, and pane respawn fail with `ExpectedToolError` so agents do not accidentally observe the wrong process.

  * MCP request method

    `tools/call` Send `capture_since` as the tool name, with the arguments below.

  ## Arguments[#](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.parameters)

  * **[`cursor`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fcursor)**? = `null` ([string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Opaque cursor returned by a prior `capture_since` call. When omitted, the tool captures the current visible screen and starts a new cursor.

  * **[`max_bytes`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fmax_bytes)**? = `128000` ([integer](https://json-schema.org/understanding-json-schema/reference/numeric "numeric (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Maximum UTF-8 bytes to return across `lines`. Defaults to `CAPTURE_SINCE_DEFAULT_MAX_BYTES`. Pass `None` to disable byte truncation.

  * **[`max_lines`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fmax_lines)**? = `500` ([integer](https://json-schema.org/understanding-json-schema/reference/numeric "numeric (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Maximum number of lines to return. Defaults to `CAPTURE_SINCE_DEFAULT_MAX_LINES`. Pass `None` to disable line truncation.

  * **[`pane_id`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fpane_id)**? = `null` ([string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Pane ID (e.g. ‘%1’). Optional when `cursor` is supplied; the cursor carries the original pane id.

  * **[`session_id`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fsession_id)**? = `null` ([string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Session ID (e.g. ‘$1’) for pane resolution.

  * **[`session_name`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fsession_name)**? = `null` ([string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Session name for pane resolution.

  * **[`socket_name`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fsocket_name)**? = `null` ([string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    tmux socket name.

  * **[`window_id`](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.input%2Fproperties%2Fwindow_id)**? = `null` ([string](https://json-schema.org/understanding-json-schema/reference/string "string (JSON Schema)") | [null](https://json-schema.org/understanding-json-schema/reference/null "null (JSON Schema)"))

    Window ID for pane resolution.

  No other arguments are accepted.

  ## Result[#](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.result)

  This server does not advertise an output schema for this tool. Its description defines the returned content.

  ## Annotations[#](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.annotations)

  * [`destructiveHint`](https://libtmux.org/en/py/stable/mcp/reference/glossary/#destructiveHint)

    `true`

  * [`idempotentHint`](https://libtmux.org/en/py/stable/mcp/reference/glossary/#idempotentHint)

    `false`

  * [`openWorldHint`](https://libtmux.org/en/py/stable/mcp/reference/glossary/#openWorldHint)

    `true`

  * [`readOnlyHint`](https://libtmux.org/en/py/stable/mcp/reference/glossary/#readOnlyHint)

    `false`

  ## Protocol data[#](https://libtmux.org/en/py/stable/mcp/tools/capture_since/#mcp.tool.capture_since.schemas)

  Use the complete advertised contract for validation and client integration.

  Input schema

  ```json
  {
    "additionalProperties": false,
    "properties": {
      "cursor": {
        "anyOf": [
          {
            "type": "string"
          },
          {
            "type": "null"
          }
        ],
        "default": null,
        "description": "Opaque cursor returned by a prior ``capture_since`` call. When\nomitted, the tool captures the current visible screen and\nstarts a new cursor."
      },
      "max_bytes": {
        "anyOf": [
          {
            "type": "integer"
          },
          {
            "type": "null"
          }
        ],
        "default": 128000,
        "description": "Maximum UTF-8 bytes to return across ``lines``. Defaults to\n``CAPTURE_SINCE_DEFAULT_MAX_BYTES``. Pass ``None`` to\ndisable byte truncation."
      },
      "max_lines": {
        "anyOf": [
          {
            "type": "integer"
          },
          {
            "type": "null"
          }
        ],
        "default": 500,
        "description": "Maximum number of lines to return. Defaults to\n``CAPTURE_SINCE_DEFAULT_MAX_LINES``. Pass ``None`` to\ndisable line truncation."
      },
      "pane_id": {
        "anyOf": [
          {
            "type": "string"
          },
          {
            "type": "null"
          }
        ],
        "default": null,
        "description": "Pane ID (e.g. '%1'). Optional when ``cursor`` is supplied; the\ncursor carries the original pane id."
      },
      "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."
      },
      "window_id": {
        "anyOf": [
          {
            "type": "string"
          },
          {
            "type": "null"
          }
        ],
        "default": null,
        "description": "Window ID for pane resolution."
      }
    },
    "type": "object"
  }
  ```