title: Streaming tools description: Three streaming tools: progress emits N progress notifications, long_output streams M chunks of K characters, chatty returns multi-block content in one result.

Streaming tools¶

Three tools that exercise progress notifications, multi-block content, and chunked output. The long-running side of MCP that gateways must forward faithfully.

progress¶

Emits N progress notifications spaced step_ms apart, then returns.

Arguments:

Field	Type	Notes
`steps`	int	Required. Default 5, max 100.
`step_ms`	int	Optional. Default 200, max 5000.

The client must include a progressToken in _meta to receive notifications. Without one, the tool runs to completion silently (notified=false in the response).

Returns:

{ "steps": 5, "notified": true, "done": true }

Side effects: N notifications/progress messages, each with:

{
  "method": "notifications/progress",
  "params": {
    "progressToken": "<client-supplied>",
    "progress": 1,
    "total": 5,
    "message": "step 1/5"
  }
}

What it tests:

Notification pass-through. Many gateways can break progress notifications by buffering the SSE stream. Set step_ms=500, steps=10, and verify the client receives 10 notifications spaced by ~500ms. If they all arrive at the end, the gateway is buffering.
Token round-trip. The progressToken in the params should match exactly between client send and server receive. A gateway that synthesizes its own tokens breaks correlation.
Cancellation mid-stream. Cancel after step 3 and verify the tool's audit row records Done: false with the correct partial step count.

long_output¶

Returns a single CallToolResult containing M text content blocks of K characters each.

Arguments:

Field	Type	Notes
`blocks`	int	Required. Default 3, max 50.
`chars`	int	Optional. Default 256, max 65536.

Returns: a CallToolResult with blocks text content items. Each block starts with [block N] and is padded to exactly chars characters.

What it tests:

Multi-block content. Verify the gateway preserves block count and order. Some gateways merge blocks, some reorder, some drop empty ones; this tool exposes those.
Per-block size limits. Bump chars until a block is dropped or truncated.
Total size limits. blocks * chars total bytes; bump until you hit the gateway's response cap.

chatty¶

Returns a CallToolResult with a fixed mix of varied text content blocks.

Arguments: none.

Returns:

{
  "content": [
    { "type": "text", "text": "first block: short" },
    { "type": "text", "text": "second block: a slightly longer string with multiple words" },
    { "type": "text", "text": "third block: numbers 1 2 3 4 5" },
    { "type": "text", "text": "fourth block: unicode; café résumé naïve" }
  ]
}

What it tests:

Unicode handling. The fourth block contains accented characters; any gateway that mis-encodes will mangle them.
Block ordering. The four blocks have a deterministic order; any reordering by the gateway shows up in a diff.
Mixed-shape content. Useful as a smoke test for content-aware enrichment that operates per-block.

Determinism guarantee¶

long_output and chatty are byte-deterministic across runs. progress notifications are byte-deterministic in shape; the wall clock between them is approximate (within a few ms of step_ms).