gong-nl-db-mcp 0.1.3

MCP server giving Claude Desktop read-only access to the BairesDev gong-nl-db Cloud SQL Postgres instance.

gong-nl-db-mcp

Read-only Claude Desktop access to the BairesDev gong-nl-db Cloud SQL Postgres instance.

This is an MCP server that colleagues install on their Mac. Once set up, they can ask Claude Desktop questions like "what tables are in gong-nl-db?" or "show me last week's top 10 accounts by call volume" and Claude will query the database directly — always read-only, always audited to their personal @bairesdev.com identity.

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For colleagues (one-time setup, ~3 minutes)

You need:

• macOS
• Claude Desktop (download)
• A Google Cloud SDK install — if you don't have gcloud:

  brew install --cask google-cloud-sdk
  

Then run:

curl -LsSf https://raw.githubusercontent.com/andyhorvitz/gong-nl-db-mcp/main/scripts/install.sh | bash

The installer will:

1. Install uv (tiny Python runner) if you don't have it.
2. Prompt you to sign in to Google with gcloud auth application-default login. Use your @bairesdev.com account.
3. Register the gong-nl-db MCP server in Claude Desktop's config.

Restart Claude Desktop and try asking it: "List the schemas in gong-nl-db."

If you get a permissions error, ping Andy — he needs to grant your Google account access to the Cloud SQL instance (see the owner setup section below).

Troubleshooting

CERTIFICATE_VERIFY_FAILED / SSL errors in Claude Desktop's logs

This is the most common failure. The installer pins the server to Python 3.12 (--python 3.12 in the Claude Desktop config), which avoids the issue entirely on a fresh install. If you hit it anyway (e.g. you installed before this fix):

# 1. Clear the cached old package
uv cache clean gong-nl-db-mcp

# 2. Re-run the installer to update your Claude Desktop config
curl -LsSf https://raw.githubusercontent.com/andyhorvitz/gong-nl-db-mcp/main/scripts/install.sh | bash

# 3. Fully quit and reopen Claude Desktop (⌘Q, not just close the window)

"Could not determine IAM DB username"

You either aren't logged in or logged in with the wrong account. Run:

gcloud auth application-default login
# Use your @bairesdev.com account when the browser opens.

Then restart Claude Desktop.

Failed to spawn process: No such file or directory

Claude Desktop launches with a stripped PATH that excludes ~/.local/bin (where uv installs its tools by default). Fix: symlink uvx into a directory Claude Desktop can see, then re-run the installer:

sudo ln -sf "$(which uvx)" /usr/local/bin/uvx
curl -LsSf https://raw.githubusercontent.com/andyhorvitz/gong-nl-db-mcp/main/scripts/install.sh | bash

The installer now writes the absolute path to uvx into the config automatically, so a fresh install won't hit this.

MCP server not appearing in Claude Desktop

Check ~/Library/Logs/Claude/ for stderr from the server. Also verify the entry exists in ~/Library/Application Support/Claude/claude_desktop_config.json under mcpServers.gong-nl-db.

What you can do

Claude will have these tools available under the gong-nl-db MCP server:

Tool	What it does
list_schemas	Show non-system schemas
list_tables(schema)	Show tables/views in a schema
describe_table(table, schema)	Show columns, types, nullability
sample_rows(table, schema, limit)	Return up to 50 sample rows
run_query(sql, limit)	Run a read-only SELECT / WITH / set-op (max 1000 rows)
explain_query(sql)	Return the query plan

What you can't do

Every query is checked against a read-only allow-list before it reaches the database. Attempting INSERT, UPDATE, DELETE, DROP, TRUNCATE, COPY, CALL, VACUUM, SET, etc. will be rejected. Even if that layer somehow let a write through, the Postgres role you connect as only has SELECT grants and the transaction is explicitly READ ONLY. Four layers of defense — you are not going to accidentally drop prod.

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For the owner (Andy): initial Cloud SQL setup

This is a one-time-per-instance setup. After this, each new colleague just needs the per-user steps below.

1. Enable IAM database authentication on the instance

gcloud sql instances patch gong-nl-db \
  --database-flags=cloudsql.iam_authentication=on,cloudsql.enable_pgaudit=on,pgaudit.log=read

2. Create the read-only Postgres role

Connect as a superuser (e.g. via cloud-sql-proxy + psql):

CREATE ROLE readonly_analysts;
GRANT CONNECT ON DATABASE <db> TO readonly_analysts;
GRANT USAGE ON SCHEMA public TO readonly_analysts;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly_analysts;
ALTER DEFAULT PRIVILEGES IN SCHEMA public
    GRANT SELECT ON TABLES TO readonly_analysts;
ALTER DATABASE <db> SET default_transaction_read_only = on;

Repeat the GRANT USAGE / GRANT SELECT / ALTER DEFAULT PRIVILEGES block for each additional schema you want to expose.

3. For each colleague (e.g. [e-mail])

# GCP IAM — lets them authenticate to the instance
gcloud projects add-iam-policy-binding <PROJECT_ID> \
  --member=user:[e-mail] --role=roles/cloudsql.client
gcloud projects add-iam-policy-binding <PROJECT_ID> \
  --member=user:[e-mail] --role=roles/cloudsql.instanceUser

# Cloud SQL — registers them as an IAM DB user on the instance
gcloud sql users create [e-mail] \
  --instance=gong-nl-db --type=cloud_iam_user

Then, in Postgres:

GRANT readonly_analysts TO "[e-mail]";

4. Configure the installer

Edit scripts/install.sh and replace the REPLACE_ME placeholders with:

• INSTANCE_CONNECTION_NAME — <project>:<region>:gong-nl-db
• DB_NAME — the Postgres database name

Commit, push to main. Next colleague who re-runs the one-liner picks up the new config.

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Development

uv venv --python 3.12
uv pip install -e ".[dev]"
.venv/bin/pytest                       # run the safety test suite

Test the MCP server locally against a running Cloud SQL Auth Proxy or the live instance:

INSTANCE_CONNECTION_NAME=... DB_NAME=... \
  .venv/bin/gong-nl-db-mcp    # speaks MCP over stdio

Releasing

Tag-driven: git tag v0.2.0 && git push --tags triggers .github/workflows/release.yml, which publishes to PyPI. Colleagues' uvx gong-nl-db-mcp@latest picks it up automatically.

The safety guarantee

src/gong_nl_db_mcp/safety.py is the statement-level allow-list. Any change to that file must go through PR review. The file's git history is the audit trail for the read-only guarantee. See tests/test_safety.py for the allow/deny corpus.