mcp: add sequential thinking server example #51

nsega · 2025-06-26T06:33:51Z

Motivation and Context

This is part of #33. This PR adds example of implementing mcp on sequentialthinking server, from Example Servers.

The PR includes dynamic and reflective problem-solving through structured thinking processes.
The server provides tools for:

starting thinking sessions
adding sequential thoughts with step tracking
revising previous thoughts
creating alternative reasoning branches
reviewing complete processes.

Also, features include thread-safe session management, adaptive planning that adjusts step counts dynamically.

How Has This Been Tested?

Testing with 8 test functions covering all functionality with test code.

Breaking Changes

N/A

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Breaking change (fix or feature that would cause existing functionality to change)
Documentation update

Checklist

I have read the MCP Documentation
My code follows the repository's style guidelines
New and existing tests pass locally
I have added appropriate error handling
I have added or updated documentation as needed

Additional context

nsega · 2025-06-26T06:35:38Z

examples/sequentialthinking/README.md

Note: Though we might not need to prepare for README.md for each example, I created this file, just in case.

It's definitely helpful.

Understood. I appreciate your input.

- This example shows dynamic and reflective problem-solving through structured thinking processes. - The server provides tools for starting thinking sessions, adding sequential thoughts with step tracking, revising previous thoughts, creating alternative reasoning branches, and reviewing complete processes. - Features include thread-safe session management, adaptive planning that adjusts step counts dynamically. - Add comprehensive testing with 8 test functions covering all functionality. For modelcontextprotocol#33

jba · 2025-06-26T11:23:50Z

After this lands, it would be great to also add it to the servers repo. See #52.

jba

I did a first round, focusing on local issues like naming.
I still don't really understand what this is doing; once I read the README more carefully I'll do another pass, probably tomorrow.

jba · 2025-06-26T11:38:17Z

examples/sequentialthinking/README.md

It's definitely helpful.

jba · 2025-06-26T11:39:11Z

examples/sequentialthinking/README.md

+- **Branch relationships**: Links to alternative reasoning paths
+- **Status management**: Active, completed, or paused sessions
+
+## Testing


You can remove this section. It is already understood.

jba · 2025-06-26T11:39:54Z

examples/sequentialthinking/main.go

+
+var httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")
+
+// Thought represents a single step in the thinking process


nit: period at end of sentence

It is my careless. Just updated it.

jba · 2025-06-26T11:43:20Z

examples/sequentialthinking/main.go

+	}
+}
+
+func (s *SessionStore) GetSession(id string) (*ThinkingSession, bool) {


Remove the Get (idiomatic Go)

Removed the Get by following idiomatic Go.

jba · 2025-06-26T11:43:47Z

examples/sequentialthinking/main.go

+
+var httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")
+
+// Thought represents a single step in the thinking process


"A Thought is..."

Updated the comment by following the format you suggested.

jba · 2025-06-26T12:58:26Z

examples/sequentialthinking/main.go

+		session.Status = "completed"
+	}
+
+	store.SetSession(session)


Addressed It.

jba · 2025-06-26T13:18:27Z

examples/sequentialthinking/main.go

+	}
+
+	var review strings.Builder
+	review.WriteString(fmt.Sprintf("=== Thinking Review: %s ===\n", session.ID))


fmt.Fprintf(&review, "...",...)

Understood. Updated these parts to using fmt.Fprint in ReviewThinking function.

jba · 2025-06-26T13:18:54Z

examples/sequentialthinking/main.go

+}
+
+// Resource handler for thinking sessions
+func GetThinkingHistory(ctx context.Context, ss *mcp.ServerSession, params *mcp.ReadResourceParams) (*mcp.ReadResourceResult, error) {


Remove Get

Addressed it.

jba · 2025-06-26T13:19:11Z

examples/sequentialthinking/main.go

+// Resource handler for thinking sessions
+func GetThinkingHistory(ctx context.Context, ss *mcp.ServerSession, params *mcp.ReadResourceParams) (*mcp.ReadResourceResult, error) {
+	// Extract session ID from URI (e.g., "thinking://session_123")
+	parts := strings.Split(params.URI, "://")


use url.Parse

Updated it to use url.Parse.

jba · 2025-06-26T13:21:53Z

examples/sequentialthinking/main.go

+
+	// Add thinking tools
+	server.AddTools(
+		mcp.NewServerTool(


Unfortunately, this will soon be a bug.
According to the spec, tools with an output schema must provide a StructuredOutput field in the result.
We don't check for that today, but I'm working on the PR.
NewServerTool creates both an input and output schema.

Can you try creating these tools without NewServerTool, using the part of NewServerTool that does input schemas, and leaving out the outputschema? It would be useful to see how complicated that gets.

Thank you for your explanation. I understand the current status of the PR you're working on.

Yes, I can. I tried to implement these tools without NewServerTool. As I may have missed something, I would appreciate it if you could provide me with further feedback on the implementation.

- Remove "Get" prefix from getter methods (idiomatic Go) - Rename Thought.ID to Thought.Index (more accurate) - Change EstimatedTotal and CreateBranch from pointers to plain types - Use zero values as "not provided" sentinel values - Fix struct comments. - Replace strings.Builder with fmt.Fprintf - Use url.Parse instead of strings.Split for URI parsing - Use slices.Collect(maps.Values()) for cleaner code Concurrency fixes: - Implement Copy-on-Write pattern to fix race conditions - Add Version field for optimistic concurrency control - Create CompareAndSwap method for atomic updates - Ensure thread-safe session modifications Tool creation: - Replace NewServerTool with manual tool creation - Avoid output schemas to prevent structured output requirement - Add explicit type conversions for JSON unmarshaling Documentation: - Remove Testing section from README per feedback - Clarify that Thought.Index is per-session, not global - Add godoc comments for all exported types and functions

nsega

Thank you so much for your feedback. I addressed the feedback. Could you please take a look at it again at your convenience?

nsega · 2025-06-27T10:01:01Z

examples/sequentialthinking/main.go

+	Thought        string `json:"thought"`
+	NextNeeded     *bool  `json:"nextNeeded,omitempty"`
+	ReviseStep     *int   `json:"reviseStep,omitempty"`
+	CreateBranch   *bool  `json:"createBranch,omitempty"`


The defaults I expected are actually:

NextNeeded : default behavior is true for continue thinking.

CreateBranch : default behavior is false for don't create a branch.

Since only CreateBranch doesn't need a pointer in this case, I updated the field from *bool to bool.

nsega · 2025-06-27T10:09:06Z

examples/sequentialthinking/main.go

+
+	sessionID := args.SessionID
+	if sessionID == "" {
+		sessionID = fmt.Sprintf("session_%d", time.Now().Unix())


Thank you for your suggestion. Since I didn't know the randText function, I am glad to have found a way to generate sufficient uniqueness. I copied randText() from util.go.

nsega · 2025-06-27T10:10:53Z

examples/sequentialthinking/main.go

+	session := &ThinkingSession{
+		ID:             sessionID,
+		Problem:        args.Problem,
+		Thoughts:       []Thought{},


You're totally right. Just omitted the field.

nsega · 2025-06-27T10:11:30Z

examples/sequentialthinking/main.go

+		ID:             sessionID,
+		Problem:        args.Problem,
+		Thoughts:       []Thought{},
+		CurrentThought: 0,


This is also you're right. Just omitted the field.

nsega · 2025-06-27T10:11:50Z

examples/sequentialthinking/main.go

+		Status:         "active",
+		Created:        time.Now(),
+		LastActivity:   time.Now(),
+		Branches:       []string{},


Just omitted the field, too.

nsega · 2025-06-27T11:02:56Z

examples/sequentialthinking/main.go

+	}
+}
+
+func (s *SessionStore) GetSession(id string) (*ThinkingSession, bool) {


Removed the Get by following idiomatic Go.

nsega · 2025-06-27T11:03:23Z

examples/sequentialthinking/main.go

+	s.sessions[session.ID] = session
+}
+
+func (s *SessionStore) ListSessions() []*ThinkingSession {


Updated the function name to Sessions.

nsega · 2025-06-27T11:03:43Z

examples/sequentialthinking/main.go

+func (s *SessionStore) ListSessions() []*ThinkingSession {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	sessions := make([]*ThinkingSession, 0, len(s.sessions))


Updated the part to use slices.Clone.

nsega · 2025-06-27T11:04:32Z

examples/sequentialthinking/main.go

+
+var store = NewSessionStore()
+
+// Tool argument structures


Added the doc for each struct respectively.

nsega · 2025-06-27T11:15:49Z

examples/sequentialthinking/main.go

+
+	// Add thinking tools
+	server.AddTools(
+		mcp.NewServerTool(


Thank you for your explanation. I understand the current status of the PR you're working on.

Yes, I can. I tried to implement these tools without NewServerTool. As I may have missed something, I would appreciate it if you could provide me with further feedback on the implementation.

nsega commented Jun 26, 2025

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nsega changed the title ~~examples: add sequential thinking server example~~ mcp: add sequential thinking server example Jun 26, 2025

nsega force-pushed the add-sequentialthinking-example branch from a71abdb to 9efbd13 Compare June 26, 2025 06:40

jba requested changes Jun 26, 2025

View reviewed changes

MegaGrindStone mentioned this pull request Jun 26, 2025

mcp: memory example #50

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nsega commented Jun 27, 2025

View reviewed changes

nsega requested a review from jba June 27, 2025 11:29

refactor: remove redundant zero-value initializations in branch session

b4ab9b1


		var httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")

		// Thought represents a single step in the thinking process

mcp: add sequential thinking server example #51

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mcp: add sequential thinking server example #51

Conversation

nsega commented Jun 26, 2025

Motivation and Context

How Has This Been Tested?

Breaking Changes

Types of changes

Checklist

Additional context

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nsega Jun 26, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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jba commented Jun 26, 2025

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nsega Jun 26, 2025 •

edited

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