This record as markdown: /tools/io-github-kivanccakmak-yaver/db-schema.md
What db_schema does on Yaver
AI agents call db_schema to retrieve information from Yaver without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
dsn | string | — | Connection string |
driver | string | Yes | Database: sqlite, postgres, mysql |
Parameters from the server's own tool schema.
Why db_schema is rated Low
This tool retrieves metadata about database structure (schema and tables) which is a read-only operation with no side effects. It does not execute queries, modify data, delete anything, or perform financial operations. The low severity reflects minimal blast radius if misused by an AI agent—schema inspection alone cannot alter system state or cause significant harm.
From the tool's definition Tool name 'db_schema' and description 'Show database schema/tables' indicate retrieval and inspection of database structure with no modification, deletion, or execution capabilities.
Attacks that exploit this kind of access
The rule that runs db_schema safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Yaver, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For db_schema, this is the rule to start with:
db_schema is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Yaver, apply this rule, and every db_schema call is checked against it from then on.
Questions about db_schema
Show database schema/tables. It is categorised as a Read tool in the Yaver MCP Server, which means it retrieves data without modifying state.
db_schema accepts 2 parameters: dsn, driver. Required: driver. The full parameter table on this page comes from the server's own tool schema.
Register the Yaver MCP server in PolicyLayer and add a rule for db_schema: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Yaver. Nothing to install.
db_schema is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the db_schema rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for db_schema. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
db_schema is provided by the Yaver MCP server (yaver-cli). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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