[JanGoebel]

Summary

Hand-tidied block diagram layout of the public API, RPC method and handler VIs. One functional change in tool call.vi: Reinitialize VI Inputs now sits on the error wire, so a tool VI's inputs are reset only when the call goes ahead, and an error while resetting them reaches the caller instead of being dropped.

	Before	After
Tool call with failing argument check	Inputs of the tool VI reset anyway	Reset skipped, error passed on
Error inside Reinitialize VI Inputs	Dropped	Passed on to Call VI and the caller

Changes

Layout only (behaviour unchanged, LabVIEW's comparison finds only cosmetic changes), modified:
Add Prompt.vi, Add Resource (File).vi, Add Tool.vi, Ask User.vi, Cancel Requested.vi, Get ID from JSON.vi, Get Server Name from ID.vi, MCP Handler/Do Request.vi, Negotiate Protocol Version.vi, Report Progress.vi, Start.vi, Stop.vi, initialize.vi, prompts get.vi, prompts list.vi, resources list.vi, resources read.vi, tool list.vi.

tool call.vi, modified: layout tidied. Reinitialize VI Inputs takes the error of Check Tool Arguments and passes its own error on to Call VI. The response chain after the call (Finish Tool Call Response, Mark Tool Error Result, Add Structured Content, Check Tool Arguments) stays without error wires on purpose: a call with missing arguments carries an error there, and these VIs must still run to turn it into a result with isError: true.

Code summary

To follow once the VI diff report has been posted by the Pull Request Review workflow (pictures in pr-assets/pr-<number>-summary).

Verified

• The branch is based on the current main (0 commits behind).
• The commit messages say LabVIEW's comparison finds only cosmetic changes in the 18 layout-only VIs. This was not re-run for this pull request.

Not verified

• Caraya suite not run locally for this pull request; the Pull Request Review workflow runs it.
• No protocol test against a running server, including a tool call with missing arguments (the case the tool call.vi change affects).
• Not checked that every VI is saved in LabVIEW 20.0 format.

Known rough edges

• The layouts were tidied by hand. Check the review report's diagrams for anything that still looks off.

🤖 Generated with Claude Code

[github-actions]

Tests

✅ All 64 tests passed.

Per-test results

Test	VI	Result	Checks
Test 1: Initialize	Test Initialize.vi	✅ pass	Assert True: pass
Test 2: Initialized	Test Initialized.vi	✅ pass	Assert True: pass
Test 3: tools/list	Test tools list.vi	✅ pass	Assert True: pass
Test 4: prompts/list	test prompts list.vi	✅ pass	Assert True: pass
Test 5: resources/list	test resources list.vi	✅ pass	Assert True: pass
Test 6: tools call	test tools call.vi	✅ pass	Assert True: pass
Test 7: empty JSON object is an invalid request	test empty msg.vi	✅ pass	Assert True: pass
Test 8: call broken tool	test broken tool.vi	✅ pass	Assert True: pass
Test 6: tools call	test tools call array.vi	✅ pass	Assert True: pass
Test 9: GET is rejected with 405	test http get rejected.vi	✅ pass	GET -> 405 with Allow: POST and error -32600: pass
Test 10: Origin validation	test http origin.vi	✅ pass	Origin http://evil.example -> 403 with error -32600: pass Origin http://localhost:6274 -> 200 with result: pass
Test 11: MCP-Protocol-Version validation	test http protocol version.vi	✅ pass	MCP-Protocol-Version 1999-01-01 -> 400 with error -32022 (Unsupported protocol version, the MCP 2026-07-28 code in both eras): pass MCP-Protocol-Version 2025-06-18 -> 200 with result: pass
Test 12: notification answered with 202	test notification accepted.vi	✅ pass	notifications/initialized -> 202 with empty body: pass
Test 13: request with id answered with 200	test request status.vi	✅ pass	tools/list with id 1 -> 200 with result and id 1: pass
Test 14: unknown method	test unknown method.vi	✅ pass	does/not/exist with id 5 -> 200 with error -32601 and id 5: pass
Test 15: unknown notification	test unknown notification.vi	✅ pass	notifications/cancelled -> 202 with empty body: pass
Test 16: ping	test ping.vi	✅ pass	ping with id 3 -> 200 with result {} and id 3: pass
Test 17: string request id	test string id.vi	✅ pass	tools/list with id "abc-1" -> 200 with result and id "abc-1": pass
Test 18: unknown prompt	test unknown prompt.vi	✅ pass	prompts/get no-such-prompt with id 7 -> JSON-RPC error -32602 with id 7, no status/source: pass
Test 19: unknown resource	test unknown resource.vi	✅ pass	resources/read of an unknown uri with id 8 -> JSON-RPC error -32002 with id 8, no status/source: pass
Test 20: resources/read returns UTF-8 text unchanged	test resource text utf8.vi	✅ pass	text of labview://fixture_utf8 decodes to the bytes of fixture_utf8.txt: pass
Test 21: resources/read returns a binary file as Base64	test resource blob.vi	✅ pass	blob of labview://fixture_binary is the Base64 of the bytes of fixture_binary.png: pass
Test 22: unknown tool	test unknown tool.vi	✅ pass	tools/call no_such_tool -> error -32602 with message Unknown tool: no_such_tool and id 22: pass
Test 23: tools/call with arguments that are not an object	test tool call without arguments.vi	✅ pass	tools/call fake_tool_add with arguments 5 -> error -32602 with message Invalid arguments... and id 23: pass
Test 24: broken tool is a tool execution error	test broken tool message.vi	✅ pass	tools/call fake_tool_broken_vi -> result with isError true and a text that says not executable: pass
Test 25: prompts/get without arguments	test prompt without arguments.vi	✅ pass	prompts/get fake_prompt_concatanate_strings without arguments -> result with messages: pass
Test 26: request without method	test request without method.vi	✅ pass	a message with id 26 and no method -> error -32600 with id 26: pass
Test 27: malformed JSON	test malformed json.vi	✅ pass	truncated JSON -> error -32700 with id null: pass
Test 28: array inputs say what their items are	test tools list array items.vi	✅ pass	fake_tool_arrays - intarray has items of type integer and stringarray of type string: pass
Test 29: protocol version negotiation	test protocol version negotiation.vi	✅ pass	initialize asking for 2024-11-05 -> protocolVersion 2024-11-05: pass initialize asking for 1999-01-01 -> protocolVersion 2025-11-25 (the newest legacy version): pass
Test 30: resources/templates/list	test resource templates list.vi	✅ pass	resources/templates/list -> result with resourceTemplates []: pass
Test 31: tools/call without arguments	test tool call default arguments.vi	✅ pass	tools/call fake_tool_add without arguments -> result with the sum 0, no error, id 31: pass
Test 32: a tool that returns an error sets isError	test tool error result.vi	✅ pass	fake_tool_return_error with status true -> result with isError true, code and source still in the content: pass fake_tool_return_error with status false -> result without isError: pass
Test 33: internal errors show no LabVIEW internals	test internal error message.vi	✅ pass	prompts/get fake_prompt_broken_vi -> error -32603 with a message without call chain, markup, tags or path: pass
Test 34: prompts/list says which arguments are required	test prompts list required.vi	✅ pass	fake_prompt_required_argument - topic has required true and style has required false: pass
Test 35: prompts/get checks required arguments	test prompt required argument.vi	✅ pass	prompts/get fake_prompt_required_argument without topic -> error -32602 that names topic, id 36: pass prompts/get fake_prompt_required_argument with topic -> result whose text contains both argument values: pass
Test 36: JSON-RPC batch	test batch.vi	✅ pass	batch of ping (id 38), a notification and tools/list (id b) -> 200 with an array of two answers in that order: pass batch of two notifications -> 202 with empty body: pass empty batch -> error -32600 with id null: pass
Test 37: a JSON value that is not an object	test non object message.vi	✅ pass	body 5 -> error -32600 with id null: pass body "text" -> error -32600 with id null: pass body null -> error -32600 with id null: pass
Test 38: tools/call checks required arguments	test tool required arguments.vi	✅ pass	tools/call fake_tool_required_input without arguments -> result with isError true and the text Missing required argument(s): b, a (the order of inputSchema.required), no JSON-RPC error, id 40: pass tools/call fake_tool_required_input with arguments {} -> result with isError true naming b and a, no JSON-RPC error, id 41: pass tools/call fake_tool_required_input with only a -> result with isError true naming only b, no JSON-RPC error, id 42: pass tools/call fake_tool_required_input with a 2 and b 3 -> result 6, no error, id 43: pass
Test 39: initialize with an unknown protocol version	test protocol version fallback.vi	✅ pass	initialize asking for 1999-01-01 -> protocolVersion is the first entry of Supported Protocol Versions.vi: pass
Test 40: initialize reports the LabVIEW version	test labview version.vi	✅ pass	initialize -> serverInfo.additionalDetails.labviewVersion equals the Version Number of this LabVIEW: pass
Test 41: tools/list shows the MCP names of special labels	test tools list mcp names.vi	✅ pass	tools/list fake_tool_special_labels -> Length (mm) and Factor #1 & 50% are listed as length__mm_ and factor__1___50_ in properties and in required, id 44: pass tools/list fake_tool_special_labels -> every name in properties and required matches ^[a-zA-Z0-9_-]{1,64}$: pass
Test 42: tools/call reaches special labels by their MCP names	test tools call mcp names.vi	✅ pass	tools/call fake_tool_special_labels with length__mm_ 2.5 and factor__1___50_ 4 -> result {"result__mm_":10}, no error, id 45: pass
Test 43: Add Tool refuses inputs whose MCP names clash	test add tool name clash.vi	✅ pass	Add Tool fake tool name clash.vi with the inputs a b and a_b -> error 5010 naming both controls and the MCP name a_b: pass tools/list after the refused Add Tool -> fake_tool_name_clash is not listed, id 46: pass
Test 44: Add Prompt refuses arguments whose MCP names clash	test add prompt name clash.vi	✅ pass	Add Prompt fake prompt name clash.vi with the arguments a b and a_b -> error 5010 naming both controls and the MCP name a_b: pass prompts/list after the refused Add Prompt -> fake_prompt_name_clash is not listed, id 47: pass
Test 45: 3D arrays and arrays of paths, enums and clusters say what their items are	test tools list array shapes.vi	✅ pass	fake_tool_array_shapes - patharray (1D array of paths) has items with a non-empty type: pass fake_tool_array_shapes - enumarray (1D array of a U16 enum) has items with a non-empty type: pass fake_tool_array_shapes - clusterarray (1D array of clusters) has items with a non-empty type: pass fake_tool_array_shapes - array3d (3D array of DBL) has items.type array, items.items.type array and items.items.items.type number: pass
Test 46: timestamps, clusters and types without a JSON type are described in tools/list	test tools list schema details.vi	✅ pass	fake_tool_schema_shapes - timestamp is a string with format date-time: pass fake_tool_schema_shapes - settings (cluster) has properties, also of its inner cluster and of its array of clusters: pass fake_tool_schema_shapes - matrix (2D array of I32) has items of type array with items of type integer: pass fake_tool_schema_shapes - variants (array of a type without JSON type) has items {}: pass fake_tool_schema_shapes - mode (U16 enum) is a string with enum [slow, fast]: pass fake_tool_array_shapes - clusterarray items and cluster with array have properties with types: pass fake_tool_array_shapes - timestamparray has items of type string with format date-time: pass
Test 47: tools/call converts timestamps, clusters, enums and 2D and 3D arrays	test tools call schema shapes.vi	✅ pass	fake_tool_schema_shapes - settings (cluster with cluster, timestamp and array of clusters) arrives unchanged: pass fake_tool_schema_shapes - matrix [[1,2],[3,4]] (2D array) arrives unchanged: pass fake_tool_schema_shapes - mode fast (enum by item name) and variants [1,"x"] (2 elements) arrive: pass fake_tool_schema_shapes with timestamp 2026-10-17T12:34:56Z -> no isError, time out 2026-10-17T12:34:56.000Z: pass fake_tool_array_shapes with a 3D array [[[1,2],[3,4]],[[5,6],[7,8]]] -> no isError, the tool gets all 8 elements: pass
Test 48: every array schema in tools/list says what its items are	test tools list every array has items.vi	✅ pass	tools/list of the test server - 21 array schemas found, 0 of them without items (expected: at least one, none without): pass
Test 49: tools/list gives element descriptions, integer ranges, data entry limits, units and defaults	test tools list descriptions defaults ranges.vi	✅ pass	fake_tool_schema_shapes - the integer items of matrix (2D array of I32) have minimum -2147483648: pass fake_tool_schema_details - mode (enum, default fast) has the default "fast": pass fake_tool_schema_details - level (U8, default 7) has minimum 0, maximum 255 and default 7: pass fake_tool_schema_details - voltage (unit V) has the description "Supply voltage. Unit: V.": pass fake_tool_schema_details - setpoint (DBL, data entry limits 0 to 100 coerced, default 25) has minimum 0, maximum 100 and default 25: pass fake_tool_schema_details - gain (no element description) has a type but no description: pass fake_tool_schema_details - config elements have their descriptions (offset, name, and enabled inside the array of clusters) and offset (I16) has minimum -32768: pass fake_tool_schema_details - count (required) has no default and has minimum -2147483648: pass
Test 50: tools/call returns structuredContent without picture outputs, and none on isError results	test tools call structured content.vi	✅ pass	tools/call fake_tool_return_error with status true (id 501) -> isError true and no structuredContent: pass tools/call fake_tool_return_error with status false (id 502) -> structuredContent carries the error cluster output as an ordinary object: pass fake_tool_picture_outputs - structuredContent holds exactly the non-picture outputs count, label, mode and time, while the text still has the picture placeholder: pass fake_tool_picture_outputs - the picture is still returned as an image item of content, and the result is not an error: pass tools/call fake_tool_required_input without arguments (id 503) -> isError true and no structuredContent: pass tools/call fake_tool_picture_outputs (id 50) -> structuredContent is present and equals the text JSON without its picture placeholder: pass
Test 51: tools/list gives an outputSchema that matches structuredContent	test tools list output schema.vi	✅ pass	fake_tool_picture_outputs - count is an integer with the description of its indicator, label is a string, and no output property has a default: pass tools/list fake_tool_picture_outputs -> outputSchema is an object schema whose properties and required are count, label, mode and time: pass tools/list fake_tool_no_inputs_outputs (no outputs) -> no outputSchema: pass fake_tool_picture_outputs - the outputSchema property names are the names in structuredContent of tools/call (id 511), and the picture output is left out: pass fake_tool_picture_outputs - time (timestamp) is a string with format date-time and mode (enum) has enum ["slow","fast"]: pass
Test 52: tools/list sends title and annotations only when they are set	test tools list title annotations.vi	✅ pass	tools/list fake_tool_add (registered without title and annotations) -> neither title nor annotations: pass tools/list fake_tool_annotated (registered with a title) -> title "Annotated Fixture Tool": pass fake_tool_annotated (readOnlyHint true, destructiveHint false, the others not set) -> annotations with exactly readOnlyHint true and destructiveHint false: pass
Test 53: modern results carry resultType, cache hints and serverInfo; legacy results do not	test modern tools list.vi	✅ pass	modern tools/list (id 53, MCP 2026-07-28 headers and _meta) -> 200 with tools, resultType complete, ttlMs 60000 and cacheScope public: pass modern tools/list -> _meta io.modelcontextprotocol/serverInfo with name and version: pass legacy tools/list (id 531, no _meta) -> tools without resultType, ttlMs, cacheScope or _meta: pass
Test 54: server/discover, and initialize never negotiates 2026-07-28	test server discover.vi	✅ pass	initialize asking for 2026-07-28 (id 541) -> the newest legacy version 2025-11-25, never 2026-07-28: pass server/discover -> capabilities tools, prompts and resources (as initialize), _meta serverInfo, ttlMs 60000, cacheScope public: pass initialize asking for 2025-11-25 (id 542) -> 2025-11-25: pass server/discover (id 54) -> 200, resultType complete, supportedVersions with 2026-07-28 and 2025-11-25: pass
Test 55: modern requests are refused when their headers do not match the body	test modern headers.vi	✅ pass	Mcp-Method prompts/list on a tools/list request (id 55) -> 400 with error -32020: pass MCP-Protocol-Version 2025-11-25 while _meta says 2026-07-28 (id 553) -> 400 with error -32020: pass tools/call with Mcp-Name =?base64?...?= of fake_tool_add, lower-case header names (id 552) -> 200 with the tool result: pass tools/call with an Mcp-Name that is not params.name (id 554) -> 400 with error -32020: pass tools/call without an Mcp-Name header (id 551) -> 400 with error -32020: pass
Test 56: unsupported versions, missing capabilities and unknown methods in the modern era	test modern errors.vi	✅ pass	modern request without io.modelcontextprotocol/clientCapabilities (id 562) -> 400 with error -32602: pass modern ping (id 564), which MCP 2026-07-28 removed -> 404 with error -32601: pass unknown version 2027-01-01 in header and _meta (id 56) -> 400, error -32022, data.supported with 2026-07-28, data.requested 2027-01-01: pass modern request with the legacy version 2025-11-25 in _meta (id 561) -> 400, error -32022, data.supported with 2025-11-25: pass modern resources/read of an unknown uri (id 565) -> error -32602 (legacy keeps -32002): pass modern request with the unknown method foo/bar (id 563) -> 404 with error -32601: pass
Test 57: elicitation by input_required and retry with inputResponses	test elicitation.vi	✅ pass	retry with inputResponses confirm_action decline (id 572) -> outcome declined: pass modern tools/call without the elicitation capability (id 573) -> outcome not supported, no input_required: pass retry with inputResponses confirm_action accept (id 571) -> complete result with outcome confirmed: pass legacy tools/call (id 574) -> outcome not supported: pass modern tools/call of fake_tool_confirm with the elicitation capability (id 57) -> resultType input_required with inputRequests.confirm_action: pass
Test 58: progress notifications as Server-Sent Events for tools/call	test progress notifications.vi	✅ pass	legacy tools/call with progressToken "t58" and Accept text/event-stream (id 581) -> HTTP 200, text/event-stream: pass id 581: the JSON-RPC result is the last data event, after progress 10: pass the tool finished all 10 steps (fixture record): pass modern tools/call with the numeric progressToken 583 (id 583) -> text/event-stream, 10 events with "progressToken":583 in order, then the complete result: pass the same call without progressToken (id 582) -> plain application/json, no progress events: pass id 581: exactly 10 notifications/progress events, each with progressToken "t58" and total 10, progress 1..10 in increasing order: pass
Test 59: closing the stream cancels a streamed tools/call	test progress cancel by close.vi	✅ pass	modern streamed tools/call over raw TCP (id 591) -> text/event-stream, the first progress event arrives: pass after the client closed the connection the tool stopped early (fewer than 10 steps) and saw cancelled? TRUE: pass
Test 60: legacy notifications/cancelled stops a streamed tools/call	test progress legacy cancel.vi	✅ pass	legacy streamed tools/call over raw TCP (id 601) -> text/event-stream, the first progress event arrives: pass the stream ended without a result for id 601: pass the tool stopped early (fewer than 10 steps) and saw cancelled? TRUE: pass notifications/cancelled for id 601 on a second connection -> HTTP 202 within 1 s, while the call runs: pass
Test 61: a client that is not in Allowed clients gets 403	test access allowed clients.vi	✅ pass	tools/list from this computer to a server that allows only 192.0.2.1 -> HTTP 403, application/json: pass the second server (port 37061, Allowed clients = [192.0.2.1]) started: pass the 403 body is the JSON-RPC error -32600 "Forbidden: client not allowed." with id null: pass
Test 62: Access token requires Authorization: Bearer	test access bearer token.vi	✅ pass	the token never appears in a response: pass no Authorization header -> HTTP 401 with WWW-Authenticate: Bearer (header names compared case-insensitively): pass Authorization: bearer test-token-62 (lower-case scheme) -> HTTP 200 with the tools/list result, no WWW-Authenticate: pass authorization: Bearer test-token-62 (lower-case header name) -> HTTP 200 with the tools/list result: pass the 401 body is the JSON-RPC error -32600 "Unauthorized: missing or invalid bearer token." with id null: pass Authorization: Bearer wrong-token -> HTTP 401 with WWW-Authenticate: Bearer: pass the second server (port 37062, Access token set) started: pass
Test 63: tools/list leaves out LabVIEW's default error cluster descriptions	test tools list error descriptions.vi	✅ pass	fake_tool_error_descriptions - the descriptions the author wrote on previous error, last error and their elements are kept unchanged, and NI's status text with a sentence added counts as the author's: pass tools/list fake_tool_error_descriptions -> error in (no error) and error out are in inputSchema and outputSchema without a description key, and so are their status, code and source; their type is still there: pass

Protocol tests

✅ Test-McpServer.ps1 passed against the test server.

Protocol tester output (0 failed required checks)

Testing MCP server at http://127.0.0.1:36987/mcp/server

[PASS] (required) Lifecycle - initialize answers 200 with a JSON result
[PASS] (required) Lifecycle - initialize answer is JSON-RPC 2.0 with the request id
[PASS] (required) Lifecycle - initialize result has protocolVersion, capabilities and serverInfo.name
[PASS] (required) Lifecycle - Content-Type of the answer is application/json
[PASS] (advisory) Lifecycle - a client asking for 2024-11-05 gets that version back
[PASS] (required) Lifecycle - notifications/initialized is accepted with 202 and no body
[PASS] (required) Transport - GET answers 405 or opens an event stream
[PASS] (advisory) Transport - 405 answer names the allowed method in an Allow header
[PASS] (required) Transport - a request from a foreign Origin is rejected (403)
[PASS] (required) Transport - a request from a localhost Origin is accepted
[PASS] (required) Transport - an unsupported MCP-Protocol-Version header is rejected (400)
[PASS] (required) Transport - the negotiated MCP-Protocol-Version header is accepted
[PASS] (required) JSON-RPC - ping is answered with an empty result
[PASS] (required) JSON-RPC - an unknown method gets error -32601 with the request id
[PASS] (required) JSON-RPC - an unknown notification is not answered
[PASS] (required) JSON-RPC - a string request id is returned unchanged
[PASS] (required) JSON-RPC - malformed JSON gets error -32700
[PASS] (advisory) JSON-RPC - a request without a method gets error -32600
[PASS] (required) Tools - tools/list returns a tools array
[PASS] (required) Tools - every tool has a name and an inputSchema of type object (1 tools)
[PASS] (advisory) Tools - array parameters say what their items are
[PASS] (required) Tools - calling an unknown tool is answered with an error
[PASS] (required) Prompts - prompts/list returns a prompts array
[PASS] (required) Prompts - every prompt has a name (1 prompts)
[PASS] (required) Prompts - getting an unknown prompt is answered with an error
[PASS] (required) Resources - resources/list returns a resources array
[PASS] (required) Resources - every resource has a uri and a name (2 resources)
[PASS] (required) Resources - reading an unknown resource is answered with an error
[PASS] (advisory) Resources - resources/templates/list returns a resourceTemplates array

Required: 24 of 24 passed. Advisory: 0 failed.

VI changes

VIs: 19 modified, 0 added, 0 deleted

VI	Changes	Changed spot, now
Add Prompt.vi src/MCP Server	cosmetic only
Add Resource (File).vi src/MCP Server	cosmetic only
Add Tool.vi src/MCP Server	cosmetic only
Ask User.vi src/MCP Server	cosmetic only
Cancel Requested.vi src/MCP Server	cosmetic only
Get ID from JSON.vi src/MCP Server	cosmetic only

13 more modified VIs

VI	Changes	Changed spot, now
Get Server Name from ID.vi src/MCP Server	cosmetic only
Do Request.vi src/MCP Server/MCP Handler	cosmetic only
Negotiate Protocol Version.vi src/MCP Server	cosmetic only
Report Progress.vi src/MCP Server	cosmetic only
Start.vi src/MCP Server	cosmetic only
Stop.vi src/MCP Server	cosmetic only
initialize.vi src/MCP Server	cosmetic only
prompts get.vi src/MCP Server	cosmetic only
prompts list.vi src/MCP Server	cosmetic only
resources list.vi src/MCP Server	cosmetic only
resources read.vi src/MCP Server	cosmetic only
tool call.vi src/MCP Server	1
tool list.vi src/MCP Server	cosmetic only

Report for commit 99289d9. The installable test package is under Artifacts of this run once the build job has finished.