Pagination

The MCP pagination spec defines opaque cursors for list-style protocol calls. FastMCP supports that protocol pagination when a server is configured with list_page_size. libtmux-mcp does not currently configure protocol-level list pagination, so its registry lists normally return as one page under FastMCP’s defaults.

Where cursors and pages show up

Protocol-level list calls

tools/list / prompts/list / resources/list / resources/templates/list are registry-list calls. In this server’s current configuration, clients should expect those lists to arrive in one response unless libtmux-mcp later enables FastMCP’s list_page_size setting.

Search result paging

One libtmux-mcp tool owns its own paging surface because a single tmux server can carry tens of thousands of pane lines:

  • search_panes readonly returns a SearchPanesResult wrapper with matches, truncated, truncated_panes, total_panes_matched, offset, and limit.

  • Agents detect truncated=True and re-call with a higher offset to page through the match set.

This is application-level paging (not MCP-cursor pagination) — the agent decides how many matches it needs and when to stop.

Observation cursors

capture_since readonly also has a cursor parameter, but it is not a pagination cursor. The first call captures the current visible pane and returns an opaque observation checkpoint. Follow-up calls pass that cursor back to receive only rows written or rewritten after the checkpoint while tmux still retains the needed history.

Because the cursor points into live tmux grid state, it has different failure modes from protocol pagination:

  • If the pane output scrolls into retained history, the cursor can still produce an exact delta.

  • If tmux clears or trims the needed history, the response sets lines_missed=True and returns a conservative current visible capture with a fresh cursor.

  • If the pane dies or is respawned, the cursor is invalid because it would otherwise point at a different process’s terminal state.

This is application-level observation, not a stable collection scan. Use it to reduce repeated pane reads, not to page through search matches.

Why separate paths

Protocol-level cursors are for collections the server owns end-to-end: the tool / prompt / resource registries.

Tool-level paging and observation cursors are for state derived from live tmux panes. Capturing every pane’s contents and running a regex is expensive, and the result set can change mid-scan (new panes open, old ones close). Repeatedly reading one pane has the opposite cost shape: the target is known, but unchanged scrollback wastes model context. libtmux-mcp exposes each contract separately instead of pretending live terminal state is one stable list.

Further reading