covdbg

com.covdbgv1.3.0Updated Oct 8, 2026

C++ code coverage on Windows for AI agents. Find uncovered code from PDBs, no rebuild.

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Overview

AI-generated overview

Lets an AI assistant measure C++ code coverage on Windows x64 binaries using existing PDB symbols, find uncovered code, and add targeted tests without…

What it does
covdbg-mcp exposes tools to run coverage on an already-built Windows x64 executable with PDB debug symbols, ranking files by uncovered lines and reading uncovered source segments with context. It can start, wait for, and cancel coverage runs, open existing .covdb databases read-only, run one read-only SQL statement, and merge databases. A guide tool offers workflow and configuration help.
When to use it
Use it when you want an assistant to close coverage gaps in a Windows C++ project: run tests, see which files and lines are uncovered, inspect that code, add a focused test, and re-run to confirm the gap is closed. It suits projects that already produce PDB symbols and do not want a rebuild for coverage.
Requirements
Windows x64, covdbg 1.3.0 or newer installed and on PATH, and an executable with PDB debug symbols. A one-time covdbg login, or the COVDBG_PROJECT_TOKEN environment variable for CI or headless use. A .covdbg.yaml next to the target executable or a config_path passed to run. The server runs locally over stdio; the MCP bundle does not include covdbg itself.
Before you install
The server starts your target executable and places probes while it runs, so it executes that program on your machine. It asks for COVDBG_PROJECT_TOKEN, a project token; keep it out of shared files. Coverage databases are written to disk, and COVDBG_OUTPUT sets a fixed default output location where later runs overwrite earlier results. The merge tool writes a combined database to an output path. covdbg's exit code does not carry the target's exit code, so check test results separately.

Installation

In SourceWeft

  1. Open covdbg in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

[covdbg]

covdbg-mcp

MCP server for covdbg: C++ code coverage on Windows for AI agents. Run tests, find uncovered code, and add targeted tests. No rebuild required.

covdbg measures coverage of the Windows x64 binaries you already build, using their PDB debug information. It works like a debugger: it starts your executable, reads the PDB, and places lightweight probes while the program runs. The MCP server is built into the covdbg executable (since v1.3.0) and is started with covdbg mcp.

This repository holds the MCP registry metadata (server.json, glama.json) and the MCP Bundle manifest (manifest.json) for covdbg. The server itself ships with covdbg.

What an agent can do

  1. Run coverage on a test executable without rebuilding it.
  2. Rank files by uncovered lines.
  3. Read the uncovered code with surrounding context.
  4. Add a focused test, re-run it, and confirm the gap is closed.
  5. Query and merge coverage databases (.covdb) with read-only SQL.

Requirements

  • Windows x64
  • covdbg 1.3.0 or newer
  • An executable with PDB debug symbols (MSVC or any PDB-producing toolchain)
  • A one-time covdbg login, or COVDBG_PROJECT_TOKEN for CI
  • A .covdbg.yaml next to the target executable, or a config_path passed to run (see the configuration reference)

Install covdbg

  • Installer (recommended): installer.msi. It installs to %LocalAppData%\Programs\Liasoft\covdbg and adds that directory to your user PATH.
  • Portable: portable.zip. Extract it anywhere and add the directory to your PATH yourself.

Then open a new terminal and sign in:

powershell
covdbg --versioncovdbg login

Client setup

The server uses stdio transport. Start it from your project directory, or pass --workspace <dir>.

Claude Code

From the project directory:

powershell
claude mcp add covdbg -- covdbg mcp

Or add a project .mcp.json:

json
{  "mcpServers": {    "covdbg": {      "command": "covdbg",      "args": ["mcp"]    }  }}

VS Code

.vscode/mcp.json:

json
{  "servers": {    "covdbg": {      "type": "stdio",      "command": "covdbg",      "args": ["mcp", "--workspace", "${workspaceFolder}"]    }  }}

Cursor

.cursor/mcp.json:

json
{  "mcpServers": {    "covdbg": {      "command": "covdbg",      "args": ["mcp"]    }  }}

Claude Desktop (MCP Bundle)

  1. Download covdbg.mcpb from the latest release.
  2. Open it with Claude Desktop, or drag it into Settings → Extensions.
  3. Set the following:
    • covdbg executable: the path to covdbg.exe. The default is the MSI install location.
    • Workspace: your project directory.
    • Project token: optional. Leave it empty if you have run covdbg login.

The bundle does not contain covdbg itself. It launches your installed covdbg.exe, so covdbg updates take effect without a new bundle.

Tools

ToolPurposeMain inputs
guideWorkflow and configuration guidanceoptional topic (config, excludes, baseline, merging, uncovered, children)
discoverFind executables and coverage databasesoptional root
runStart a coverage run; returns a run session right awaytarget; optional target_arguments, config_path, output_path, follow_children
wait_runWait briefly or collect the completed resultsession_id; optional timeout_seconds
cancel_runTerminate a runsession_id
open_coverageOpen an existing database read-onlypath
filesRank files by uncovered linessession_id; optional limit, max_coverage_percent
codeRead uncovered source segments with contextsession_id, file_path
queryRun one read-only SQL statementsession_id, sql; optional max_rows
mergeCombine databasesinput_paths, output_path
closeRelease a run or coverage sessionsession_id

Limits and behavior

  • Run session IDs start with run-; coverage session IDs start with covdb-.
  • At most 8 runs in flight and 32 open coverage sessions.
  • wait_run blocks for at most 30 seconds. If it reports stillRunning, call it again.
  • Run outcomes are success, no_functions_to_track, license_failure, or error.
  • covdbg's exit code does not carry the target's exit code, so check test results separately.

Environment variables

VariablePurpose
COVDBG_PROJECT_TOKENProject token for CI or headless use. Local use relies on covdbg login.
COVDBG_OUTPUTFixed default output location. Avoid reusing one location across a suite, since later runs overwrite earlier results.

Documentation

Publishing (maintainers)

Keep version in manifest.json and server.json, and the release tag in the server.json package URL, in sync.

  1. Build the bundle. .mcpbignore limits it to manifest.json, icon.png and LICENSE:

    powershell
    npx @anthropic-ai/mcpb validate manifest.jsonnpx @anthropic-ai/mcpb pack . covdbg.mcpb

  2. Create the GitHub release v<version> and upload covdbg.mcpb as an asset.

  3. Put the bundle's hash into fileSha256 in server.json:

    powershell
    (Get-FileHash covdbg.mcpb -Algorithm SHA256).Hash.ToLower()

  4. Publish to the MCP registry. The com.covdbg/* namespace uses DNS authentication on covdbg.com:

    powershell
    mcp-publisher login dns --domain covdbg.com --private-key <key>mcp-publisher publish

  5. Glama picks up glama.json from the repository.

License

The metadata in this repository is licensed under the Apache License 2.0. covdbg itself is licensed separately, with Free, Team, and Enterprise plans. See covdbg.com and the Licensing FAQ.

Source: README.md at commit e081067

Tools

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Version history

1
  1. v1.3.0LatestOct 8, 2026