Is Sequential Thinking MCP server safe?

What Sequential Thinking MCP server does

This server provides a single sequential_thinking tool that helps a model work through a problem in numbered steps, revise earlier thoughts, branch into alternative lines of reasoning and adjust how many steps it plans. The npm author field names Model Context Protocol a Series of LF Projects, LLC. Its documentation describes no file, credential or external service access; the tool receives the thinking steps the model sends and, by default, logs them. Before installing, decide whether you want that content logged: setting DISABLE_THOUGHT_LOGGING to true turns the logging off.

No malicious indicators - review capabilities before installing

Notable — review in context (a capability is not a malicious indicator):

npm prepare hook
MCP tool surface detected

What to do: Nothing here argues against installing it. Grant the capabilities it lists only if you expect the tool to need them.

Sequential Thinking MCP server is an MCP server analyzed by SkillTotal's deterministic static scanner. The scan found no malicious indicators. It can: install time execution and mcp tools detected — capabilities are what the code can do, not a verdict on intent. Risk score 0/100 (low).

@modelcontextprotocol/server-sequential-thinking 2.1.1

npm package · npm:@modelcontextprotocol/server-sequential-thinking

LOW

/ 100 risk score

Snapshot · scanned Nov 13, 2026 · @modelcontextprotocol/server-sequential-thinking@2.1.1 · engine 1.1.0 / ruleset 100

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Automated static-analysis result. It can contain false positives and false negatives, and is not a claim about the intent of Sequential Thinking MCP server's authors. Report a false positive.

Capabilities — what this component can do (not a risk score):

install time executionmcp tools detected

Behavioral traits

How this component maps to the CSA agentic threat model. Descriptive — it never affects the risk score.

Tool surface

Tool Usage

Supply-chain provenance risk

General Protections / Supply Chain

Findings (2)

Capabilitynpm prepare hooknot scored · severity mediumST-INSTALL-NPM-PREPARE

package.json has a 'prepare' script (runs on git/local installs and before publishing).

package.json:26

"prepare": "npm run build",

Why it matters: Usually a build step, but confirm it doesn't fetch or run remote code.

Fix: Usually a legitimate build step; confirm it only builds and does not fetch or execute remote code.

CapabilityMCP tool surface detectednot scored · severity lowST-MCP-DETECTED

An MCP tool surface (manifest or tool definitions) was found.

dist/index.js:41

const server = new McpServer({

dist/index.js:46

server.registerTool("sequentialthinking", {

Why it matters: Just context — review which tools it offers and their permissions.

Fix: Review the declared MCP tools and their permissions.

How attackers abuse these capabilities

Interactive labs on the attack class behind the rules above. They show the technique, not anything found in Sequential Thinking MCP server.

Install Script lab

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How we determine this: deterministic static analysis (regex + AST), evidence-anchored, no code execution. Methodology →