DBJavaGenix

db_render_er_diagram

Generate Mermaid ER diagrams for multiple database tables to visualize relationships, foreign keys, and columns using an established connection.

Instructions

生成多个表的 Mermaid ER 图 (MCP App: mermaid 组件)。调用前需已通过 db_connect_test 建立连接。支持 MCP Apps 的客户端会渲染图表;不支持的客户端会看到纯文本摘要 + mermaid 源码。

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "connection_id": "<connection_id>",
      "database": "<database>",
      "tables": "<tables>"
    },
    "name": "db_render_er_diagram"
  }
}

Input Schema

Name	Required	Description
`connection_id`	Yes	Database connection ID from db_connect_test
`database`	Yes	Database name
`tables`	Yes	表名列表 (至少 1 个)
`include_non_pk_columns`	No	是否列出非主键/外键列 (默认 true)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.1May 26, 2026

TDQS

A3.6/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description bears full responsibility. It reveals the tool uses Mermaid and the MCP App component, and that unsupported clients see a plain text summary plus source. However, it does not discuss side effects, read-only nature, or error handling.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description consists of two concise sentences with no superfluous information. It front-loads the purpose and immediately adds prerequisites and behavior, making it efficient for an agent to parse.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no output schema, the description adequately covers the return format (rendered diagram or plain text + source) and the prerequisite. It lacks details on error handling or performance, but is otherwise complete for a diagram-generation tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so baseline is 3. The description does not add extra meaning beyond the schema beyond implicitly mentioning 'multiple tables' for the 'tables' parameter. No parameter-specific details or examples are given.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states the tool generates Mermaid ER diagrams for multiple tables, which is a specific verb and resource. While it does not explicitly distinguish from siblings, the purpose is clear and distinct from other db_* tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description includes a clear prerequisite: must have established a connection via db_connect_test before calling. However, it does not provide guidance on when not to use this tool or suggest alternatives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.