Ast Impact Mapper MCP server

by vola-trebla·io.github.vola-trebla/ast-impact-mapper-mcp·v0.3.1

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MCP server that uses TypeScript AST to find which tests are affected by a code change

C63/100grade C

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Safety scan

C63/100

full report

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If you have run it, two minutes of your experience saves the next person an afternoon.

Ast Impact Mapper tools (15, 1 write)

write = sends, deletes, buys or posts

Read from the package source without running it. The installed server may list more.

analyze_api_surface_mutation
Compares a file against its HEAD version and classifies the change as
detect_architectural_cycles
Detects circular import dependencies — A imports B which imports C which imports A.
differentiate_type_impact
Classifies each changed file as type-only or runtime, then splits affected tests into
explain_impact
Finds the exact import chain that connects a changed source file to a test file.
generate_skeleton_view
Generates a token-optimized representation of a source file by stripping function and method bodies, keeping only JSDocs and declarations with line numbers.
generate_test_command
Outputs the optimal test execution command for Jest, Vitest, or Playwright based on changed files.
get_affected_tests
Given a list of changed source files, returns which test files are affected —
get_affected_tests_by_branchwrite action
Runs `git diff --name-only <base_branch>...HEAD` internally and returns affected test files.
get_coverage_gaps
Finds source files that are not reachable from any test file through the import graph —
get_dependency_graph
Returns the direct import graph for a specific file:
get_rename_aware_diff
Like get_affected_tests_by_branch, but correctly handles renamed and moved files.
get_symbol_dependency_graph
Retrieves a bidirectional or directed dependency graph mapped to individual declarations, functions, and variables.
get_test_summary
Returns a bird's-eye view of the project's test structure: coverage rate,
identify_unreachable_modules
Finds source files that are never imported by any other file — dead code candidates safe to delete.
refresh_project
Clears the cached AST for a project root, forcing a full re-parse on the next call.

Public scan report

scanner v0.1.9 · 2026-09-27 · same rubric, same numbers if you re-run it

1 high

Code scan8 source files scanned13/25
–Live reliabilityno gateway calls yet and no remote to proben/a
–Tool poisoningtools not inspected (local package is not executed); not countedn/a
Auth qualitylocal package, no credentials required12/15
Maintenancelast push 129 days ago8/15
Maintainer identityregistry namespace matches repository owner; GitHub account older than a year8/10

Findings (1)

highShell command built from a string (injection risk)exec.shell-concat

dist/analyzer.js: …fOutput; try { diffOutput = execSync(`git diff --name-only ${baseBranch}...HEAD`, { cwd: …

Overall 63/100. Components that don't apply are left out of the denominator. Any critical finding is an F.Rubric Appeal a finding JSON

How Ast Impact Mapper compares

Against every graded MCP server, from our own scans and uptime checks. Updated after each scan run.

Safety score: 63/100; higher than 18% of 48,273 servers
Tools: 15; the typical server has 7
Tools that change things: 7%; typical: 0%. Fewer write tools means less an agent can break

What its tools let an agent do: 12 read · 2 create · 1 change

Install Ast Impact Mapper in Claude Code, Cursor or VS Code

Runs npx -y ast-impact-mapper-mcp on your machine. Read the scan report first; the gateway never runs local packages.

claude mcp add ast-impact-mapper-mcp -- npx -y ast-impact-mapper-mcp

Add to Cursor

What the publisher says

From the Ast Impact Mapper repository's README, as published. We do not edit it. Read it on GitHub

🗺️ ast-impact-mapper-mcp ✨

"Stop boiling the ocean. Run only the tests that actually care about your changes." 🐸

ast-impact-mapper-mcp is an advanced Model Context Protocol (MCP) server that analyzes your TypeScript/JavaScript codebase using AST parsing (ts-morph) and dependency graph tracing. It helps AI agents (like Claude or Cursor) target only the relevant tests, find dead code, identify circular import dependencies, and trace API mutations.

🧐 Why import graphs?

Guessing affected tests based on matching filenames (e.g. auth.ts -> auth.test.ts) is highly inaccurate. Running the entire test suite on every minor change is extremely slow.

Import graphs do not lie. If a test file transitively imports a modified source file, it must be run. ast-impact-mapper-mcp builds a bidirectional file dependency graph and answers "which tests should I run?" in milliseconds.

💡 Quick Showcase (Real-World e2e Flow)

Imagine your AI agent modifies a shared helper: src/utils/auth.ts. Instead of blindly running all tests or guessing by name, the agent uses this MCP server:

1. Identify Affected Tests

The agent calls getaffectedtests with the changed file:

// Tool Call: get_affected_tests({ changed_files: ["src/utils/auth.ts"] })
{
  "changed_files": ["/project/src/utils/auth.ts"],
  "affected_tests": ["/project/tests/checkout.spec.ts"],
  "total_affected": 1
}

2. Explain the Connection

To understand why checkout.spec.ts depends on auth.ts, the agent calls explain_impact:

// Tool Call: explain_impact({ changed_file: "src/utils/auth.ts", test_file: "tests/checkout.spec.ts" })
{
  "found": true,
  "import_chain": [
    "/project/tests/checkout.spec.ts",
    "/project/src/fixtures/user-fixture.ts",
    "/project/src/utils/auth.ts"
  ]
}

Aha! The checkout spec imports the user-fixture, which imports auth!

3. Check for Runtime Impact

If the change in auth.ts was only adding a TypeScript interface (type-only change), calling differentiatetypeimpact tells the agent:

{
  "files": [{ "file": "/project/src/utils/auth.ts", "runtime_impact": false }],
  "total_tests_must_run": 0,
  "total_tests_skippable": 1
}

Success! Since it is a type-only change, the agent can skip running tests entirely, saving precious CPU cycles and time.

4. Run Minimal Tests

If it does contain runtime changes, the agent requests the execution command:

// Tool Call: generate_test_command({ changed_files: ["src/utils/auth.ts"], runner: "vitest" })
{
  "command": "npx vitest run tests/checkout.spec.ts"
}

🛠️ MCP Tools Reference

All tools are configured with consistent, type-safe schemas (arguments in snake_case).

1. Impact Mapping & Tracing

#### getaffectedtests

Finds all test files transitively importing changed source files.

Arguments:
project_root (string, required): Absolute path to the TypeScript project.
changed_files (string[], optional): Modified file paths.
git_diff (string, optional): Raw stdout of git diff --name-only.
Returns: Detailed map of changed files, affected tests, and totals.

#### getaffectedtestsbybranch

Shortened. The full README is on GitHub.

Nothing above is checked by us. What we check is on the safety report.

Ast Impact Mapper: common questions

Is Ast Impact Mapper MCP server safe?: With care: it is graded C, so read the findings first (63/100). Read the Ast Impact Mapper safety report
How do I install Ast Impact Mapper?: It runs on your machine. Copy the Claude Code, Cursor, VS Code or Claude Desktop config from the install section.
Does Ast Impact Mapper need an API key?: Not as far as the registry entry and our scan can tell: no credentials are declared or required.
Is Ast Impact Mapper maintained?: The last commit was 165 days ago (2026-05-21). The latest release is v0.3.1.
How does Ast Impact Mapper compare with other MCP servers?: safety score 63/100 (higher than 18% of 48,273 servers); tools 15 (the typical server has 7); tools that change things 7% (typical: 0%. Fewer write tools means less an agent can break). Full comparison.