Data Platform MCP

by 1franky

Overview Schema Source Related Servers Discussions Admin

Python

Hybrid

explain_query

Retrieve a PostgreSQL JSON execution plan for any SELECT statement, bypassing ANALYZE.

Instructions

Return a JSON PostgreSQL plan for a SELECT without using ANALYZE.

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>",
      "sql": "<sql>"
    },
    "name": "explain_query"
  }
}

Input Schema

Name	Required	Description	Default
`sql`	Yes
`parameters`	No
`connection_id`	Yes
`timeout_seconds`	No

Output Schema

Name	Required	Description
`plan`	No
`analyze`	No
`message`	Yes
`explained`	Yes
`error_code`	No
`validation`	Yes	Complete result of parsing and applying the read-only policy.
`duration_ms`	No
`connection_id`	Yes
`explained_sql`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.9.0Aug 5, 2026

TDQS

C2.9/5.0

Behavior2/5

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

With no annotations, the description carries full responsibility for disclosing behavior. It notes that ANALYZE is not used, implying the query is not executed, but it does not explicitly state that the operation is read-only or side-effect-free. It also does not mention any permissions, rate limits, or prerequisites, leaving the agent to infer safety and behavior.

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 is a single sentence that is directly on point, with no filler or redundant information. It front-loads the core purpose and is appropriately sized for the tool's simplicity.

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

Completeness2/5

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

Despite having an output schema, the description offers minimal context for a tool with four parameters and no annotations. It does not clarify the meaning of the JSON plan, parameter usage, or when to select this tool over related siblings. The description is too sparse for the tool's complexity, leaving significant gaps in guidance.

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

Parameters1/5

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

The schema has 0% description coverage, and the description does not compensate by explaining any of the four parameters (sql, parameters, connection_id, timeout_seconds). The agent is left with no understanding of what each parameter means, how they interrelate, or what formats are expected beyond raw schema types.

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

Purpose5/5

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

The description clearly states the tool returns a JSON PostgreSQL plan for a SELECT query without executing it, which distinguishes it from siblings like execute_read_query and validate_sql. It uses a specific verb ('Return') and resource ('PostgreSQL plan for a SELECT'), leaving no ambiguity about its core function.

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

Usage Guidelines2/5

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

The description provides no explicit guidance on when to use this tool versus alternatives. It only scopes the tool to SELECT queries, but does not mention when a plan is needed, what to do for non-SELECT statements, or how this compares to validate_sql or execute_read_query. No exclusion criteria or alternative tools are referenced.

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