Secure Schema MCP
Provides read-only schema inspection for MySQL databases, exposing table and view names, columns, types, keys, and relationships without exposing row data.
Provides read-only schema inspection for PostgreSQL databases, exposing table and view names, columns, types, keys, and relationships without exposing row data.
Provides read-only schema inspection for SQLite databases, exposing table and view names, columns, types, keys, and relationships without exposing row data.
Click on "Install Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type
@followed by the MCP server name and your instructions, e.g., "@Secure Schema MCPshow me the schema of the orders table"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Secure Schema MCP
A read-only MCP server that gives AI coding tools database structure without exposing row data. It returns table and view names, columns, types, keys, and relationships in a compact format designed to reduce LLM token usage.
What it exposes
Exposed | Not exposed |
Table and view names | Row values or query results |
Column names and SQL types | Row counts or samples |
Primary and unique keys | Database credentials |
Foreign-key relationships | Write or query tools |
Schema metadata can still be sensitive. A column name such as ssn reveals information even without values, so production deployments should always use the table allowlist and a dedicated database account.
Related MCP server: DBMCP
Requirements
An MCP-compatible client such as Cursor or Codex
A reachable SQLite, PostgreSQL, or MySQL database
Python 3.12 or newer when installing without
uvx
SQLite support uses Python's built-in driver. PostgreSQL and MySQL drivers are included. Other SQLAlchemy dialects are not tested or bundled in v1.
Configure your IDE
The recommended setup uses uvx to download and run the published Python package in an isolated environment. You do not need to clone this repository or start the server separately. Your IDE launches it over stdio when needed.
Cursor
Add this server to your Cursor MCP configuration:
{
"mcpServers": {
"secure-schema": {
"command": "uvx",
"args": ["mcp-secure-schema"],
"env": {
"DATABASE_URL": "postgresql+psycopg2://schema_reader:password@localhost:5432/appdb",
"DATABASE_SCHEMA": "public",
"ALLOWED_TABLES": "users,orders,products",
"SECURE_SCHEMA_ENV": "production",
"FASTMCP_CHECK_FOR_UPDATES": "off",
"FASTMCP_SHOW_SERVER_BANNER": "false"
}
}
}
}Restart or reload Cursor after changing its MCP configuration.
Codex
Add this to ~/.codex/config.toml or a trusted project's .codex/config.toml:
[mcp_servers.secure-schema]
command = "uvx"
args = ["mcp-secure-schema"]
enabled_tools = ["schema_overview", "list_tables", "inspect_table"]
startup_timeout_sec = 30
tool_timeout_sec = 30
[mcp_servers.secure-schema.env]
DATABASE_URL = "postgresql+psycopg2://schema_reader:password@localhost:5432/appdb"
DATABASE_SCHEMA = "public"
ALLOWED_TABLES = "users,orders,products"
SECURE_SCHEMA_ENV = "production"
FASTMCP_CHECK_FOR_UPDATES = "off"
FASTMCP_SHOW_SERVER_BANNER = "false"Install once instead
If you prefer a persistent installation:
pipx install mcp-secure-schemaThen use "command": "mcp-secure-schema" with an empty args list in the IDE configuration.
Database URLs
Secure Schema MCP accepts SQLAlchemy connection URLs:
# SQLite (absolute path)
sqlite:////Users/me/project/app.db
# PostgreSQL
postgresql+psycopg2://user:password@localhost:5432/appdb
# Remote PostgreSQL with certificate verification
postgresql+psycopg2://user:password@db.example.com:5432/appdb?sslmode=verify-full&sslrootcert=/path/to/ca.pem
# MySQL
mysql+pymysql://user:password@localhost:3306/appdbPercent-encode special characters in URL usernames and passwords. For example, @ in a password becomes %40.
Local and remote databases use the same MCP configuration. For remote databases, the machine running the IDE must also have working DNS, network access, firewall permission, and valid TLS settings.
Configuration
Variable | Required | Description |
| Yes | SQLAlchemy connection URL. Treated as a secret by the registry manifest. |
| No | Default schema or catalog namespace. Recommended for PostgreSQL. Locked against tool overrides in production. |
| Production | Comma-separated, case-sensitive table and view allowlist. Production mode refuses to start without it. |
| No | Set to |
| No | Set to |
| No | Set to |
Multiple schemas
DATABASE_SCHEMA selects the default namespace. Resolution works as follows:
In production, a configured
DATABASE_SCHEMAis a security boundary and tool arguments cannot override it.Outside production, an explicit tool
schemaargument overridesDATABASE_SCHEMA.Without either value, the database driver's default schema is used.
For strict production access to multiple schemas, run one MCP server entry per schema with its own DATABASE_SCHEMA and ALLOWED_TABLES values. The table allowlist contains unqualified names, not schema.table values.
Tools
schema_overview: compact map of permitted tables, views, primary keys, and foreign-key relationshipslist_tables: permitted table and view inventoryinspect_table: columns, SQL types, nullability, primary keys, unique constraints, and foreign keys for one entity
Every tool defaults to format="compact" for lower token usage:
tables:orders,users | pk:orders(order_id);users(user_id) | fk:orders.user_id->users.user_idPass format="markdown" when a human-readable table is more useful.
Security notes
The server exposes only SQLAlchemy inspection operations; it provides no row-query or write tool.
Missing and disallowed table names return the same message when an allowlist is active, avoiding an existence leak.
Client-facing errors are sanitized. Operational details are written to server stderr.
The IDE launches the MCP process and supplies its environment, so treat the IDE and its configuration as trusted.
Do not commit configurations containing credentials. For stronger isolation, launch through a wrapper that obtains
DATABASE_URLfrom an OS keychain or secret manager.Use a dedicated least-privilege database account and TLS certificate verification for remote connections.
Example PostgreSQL role:
CREATE ROLE schema_reader LOGIN PASSWORD 'use-a-secret-manager';
GRANT CONNECT ON DATABASE appdb TO schema_reader;
GRANT USAGE ON SCHEMA public TO schema_reader;Metadata visibility varies by PostgreSQL provider and database policy. Grant only the additional catalog or object privileges required for inspection; avoid granting row SELECT unless your environment requires it.
Troubleshooting
The server exits immediately
Check the IDE's MCP logs. DATABASE_URL is mandatory, and production mode also requires a non-empty ALLOWED_TABLES value.
No tables or views are discovered
Confirm DATABASE_SCHEMA, exact table-name casing, database permissions, and whether the allowlist contains the expected names.
The connection URL fails with a valid password
Percent-encode reserved URL characters or use a secret-injection wrapper. Do not paste real credentials into issues or logs.
uvx is not found
Install uv using its official instructions, or install the package with pipx and use mcp-secure-schema as the command.
Starting the command appears to hang
That is normal for a stdio MCP server. It waits for an MCP client on standard input and is normally started by the IDE.
Development
Clone the repository only when developing or testing the server:
git clone https://github.com/Siddharth-coder13/secure_schema_mcp.git
cd secure_schema_mcp
uv sync --extra dev
uv run python tests/demo_database.py
DATABASE_URL="sqlite:///$PWD/test_schema.db" uv run mcp-secure-schemaRun the test suite:
uv run pytestRun the opt-in PostgreSQL integration test against a disposable database. The test creates and removes a randomly named schema:
POSTGRES_TEST_DATABASE_URL='postgresql+psycopg2://user@localhost:5432/testdb' \
uv run pytest tests/test_postgres_smoke.py -vThe tests verify row-data isolation, allowlist behavior, sanitized errors, compact output, relationships, schema selection, and the locked production namespace.
Release checklist
Maintainers should update the matching versions in pyproject.toml and server.json, run the complete SQLite and PostgreSQL suites, build with uv build --no-sources, verify installation from the wheel, publish to PyPI, and only then publish server.json to the MCP Registry.
License
Licensed under the Apache License 2.0. See LICENSE and NOTICE.
Available Tools
3 toolsinspect_tableA
Exposes exact column names, types, nullability, primary keys, and foreign key relationships. Strictly constrained to structural layouts. Does not reveal data rows.
| Name | Required | Description | Default |
|---|---|---|---|
| format | No | Output format. Use compact to reduce LLM token usage; markdown for human-readable output. | compact |
| schema | No | Optional schema/catalog namespace. Overrides DATABASE_SCHEMA only outside production. | |
| table_name | Yes | The exact case-sensitive name of the table to inspect. |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description handles disclosure by stating it only returns structural metadata and no data rows. It could mention it is read-only or has no side effects, but the current text is still adequately transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, no fluff. The first sentence captures the essential purpose, and the second clarifies constraints. Very efficient.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given an output schema exists (not shown), the description does not need to detail return values. It covers the tool's scope adequately, though it could benefit from mentioning permissions or performance.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, and the description adds no extra parameter info beyond what the input schema already provides. Baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool exposes column names, types, nullability, primary keys, and foreign key relationships. It is distinct from sibling tools like list_tables and schema_overview by specifying 'structural layouts' and explicitly noting it does not reveal data rows.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies use for structural inspection only via 'Does not reveal data rows,' but lacks explicit when-to-use or when-not-to-use guidance, nor does it reference sibling tools for data queries.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
list_tablesA
Lists all user tables and views available in the current database. Use this to understand what architectural entities exist.
| Name | Required | Description | Default |
|---|---|---|---|
| format | No | Output format. Use compact to reduce LLM token usage; markdown for human-readable output. | compact |
| schema | No | Optional schema/catalog namespace. Overrides DATABASE_SCHEMA only outside production. |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It discloses that it lists 'all' tables and views, which implies a read operation. However, it does not state that it is non-destructive, read-only, or if there are any performance implications. For a simple listing tool, this is acceptable but could be more explicit.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences: the first defines the action, the second provides usage guidance. It is concise, front-loaded, and every word earns its place. No redundancy or unnecessary information.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with 2 simple parameters, no required fields, and an output schema, the description is adequately complete. It covers what the tool does and when to use it. It does not mention edge cases like system tables or performance, but given the low complexity, it is sufficient.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100% with detailed descriptions for both parameters. The tool description does not add additional meaning beyond what is already in the schema. Therefore, the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states it 'Lists all user tables and views available in the current database.' This is a specific verb and resource, and it distinguishes from siblings like 'inspect_table' (which inspects a single table) and 'schema_overview' (which likely gives a broader schema summary). The purpose is explicit.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description includes 'Use this to understand what architectural entities exist,' which provides clear context for when to use the tool. However, it does not explicitly state when not to use it or compare it to alternatives (siblings), so it slightly lacks in exclusion guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
schema_overviewA
Summarizes available tables, views, primary keys, and foreign key relationships. Strictly constrained to structural metadata. Does not reveal data rows.
| Name | Required | Description | Default |
|---|---|---|---|
| format | No | Output format. Use compact to reduce LLM token usage; markdown for human-readable output. | compact |
| schema | No | Optional schema/catalog namespace. Overrides DATABASE_SCHEMA only outside production. |
Output Schema
| Name | Required | Description |
|---|---|---|
| result | Yes |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations provided, so description carries full burden. It discloses that only structural metadata is returned, no data rows, and mentions output format options. This adequately sets expectations for a read-only, non-destructive tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences, no redundant text. The purpose and key constraints are front-loaded. Every word earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity, presence of an output schema, and high schema description coverage, the description is complete. It explains scope, constraints, and parameter nuances sufficiently.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%. The description adds value beyond the schema: for 'format' it explains token usage vs human readability, and for 'schema' it clarifies it only overrides outside production. This helps the agent decide parameter values.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly states the tool summarizes structural metadata including tables, views, primary keys, and foreign keys. It explicitly distinguishes from sibling tools by noting it does not reveal data rows, indicating a broader scope than inspect_table or list_tables.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description implies usage for structural overview but does not explicitly compare to sibling tools or state when to use which. The constraint 'Strictly constrained to structural metadata' gives context but lacks explicit guidance on alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections. Dates show when Glama detected each change.
3 tool updates
v1.0.1- First observed
inspect_table - First observed
list_tables - First observed
schema_overview
TDQS
list_tables and schema_overview both list tables/views, creating overlap. inspect_table is distinct but also covers PK/FK info that schema_overview summarizes. Descriptions help distinguish, but ambiguity remains.
Two tools use verb_noun pattern (inspect_table, list_tables), while schema_overview uses noun_noun. The inconsistency is minor but noticeable.
Three tools is appropriate for a focused schema exploration server. The count covers essential operations without being excessive.
Covers listing tables, detailed table inspection, and schema summary. Minor gaps like lack of view-specific inspection or filtering, but overall the surface is sufficient for the domain.
Maintenance
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