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Documentation Index

Fetch the complete documentation index at: https://isthmus.dev/docs/llms.txt

Use this file to discover all available pages before exploring further.

Isthmus exposes three MCP tools that AI models call to explore and query your PostgreSQL database. You don’t call these tools directly — your AI client (Claude, Cursor, etc.) invokes them automatically based on your questions. When an AI model connects to your database for the first time, the most effective sequence is: 
1. discover          → What schemas and tables exist? (sizes, row counts, columns)
2. describe_table    → Full table analysis: columns, types, keys, stats, sample rows, index usage
3. query             → Execute a read-only SQL query (with optional EXPLAIN plan)
Most AI models follow this pattern naturally — they start broad with discover, narrow down to specific tables with describe_table, then write and execute SQL with query.

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Tool summary

ToolPurposeParameters
discoverFull database landscape: schemas with nested tables(none)
describe_tableComplete table analysis: columns, statistics, sample rows, index usagetable_name (required), schema
queryExecute read-only SQL with optional EXPLAIN planssql (required), explain, analyze

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Safety guardrails

All tools operate within Isthmus’s safety model:
  • Read-only transactions — queries cannot modify data
  • SQL validation — only SELECT and EXPLAIN statements are allowed (enforced via PostgreSQL AST parsing)
  • Row limits — configurable max rows per query (default: 100)
  • Query timeout — configurable timeout (default: 10s)
  • Schema filtering — only expose the schemas you choose
See Security for the full safety model.