MSSQL MCP DescribeTable tool only works with SQL Server 2017 (14.x) and later

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#61 opened on Aug 1, 2025 0 comments 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty: 3/5
Estimated time: 1-2 days
Newbie friendliness: 38/100

Issue type: Bug
Clarity: Mostly clear
Activity status: Stale
Tech stack: sql
Domain: databases

Research direction

Start at the MSSQL MCP DescribeTable implementation and inspect the query using STRING_AGG. Reproduce the failure against a database with compatibility level below 140, then determine whether the tool should support that level and verify the chosen behavior against an older SQL Server compatibility setting.

Written by the indexing model from the issue text.

Description

MSSQL MCP DescribeTable tool fails with error

{"success":false,"error":"Incorrect syntax near \u0027(\u0027."}

when used with an old SQL server version (or, in my case, a database with a compatibility level lower than 140).

This happens because the STRING_AGG SQL function, which is used in the implementation of DescribeTable, was only introduced in SQL Server 2017 (14.x).

There are other approaches that accomplish the same thing and also work with older version of SQL server, but probably it's not worth it to introduce such a workaround for such old versions.

I was able to work around this issue by increasing the compatibility level of my local database:

alter database current set compatibility_level = 160;

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