Skip to main content
Glama
Sign In
Lagaam

Lagaam

Official
by lagaam-ai
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Remote

Describe table

describe_table
Read-only

Retrieve a table's exact column names and data types before writing queries, using read-only metadata so you avoid guessing columns and querying rows.

Instructions

Get the exact columns and types of one table. Read-only.

    Always describe a table before querying it; column names you have
    not seen here are guesses. It reads the engine's metadata and
    statistics, never the table's rows. A table outside your grant is
    refused before the engine is asked; a missing one errors with a
    pointer to list_catalogs. Answers are cached, 5 minutes by default,
    so a new column can lag. row_estimate is the engine's row-count
    statistic, null when it has none or can't be trusted (views, tables
    without stats, Pinot tables with a realtime part). Column comments
    are null when unset, and always on Pinot.

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": {
      "catalog": "<catalog>",
      "schema": "<schema>",
      "table": "<table>"
    },
    "name": "describe_table"
  }
}

Input Schema

NameRequiredDescriptionDefault
tableYesTable name as list_catalogs shows it.
schemaYesSchema name as list_catalogs shows it. On Pinot a schema is a Pinot database, such as `default`.
catalogYesCatalog name as list_catalogs shows it. On Pinot it is always `pinot`.

Output Schema

NameRequiredDescriptionDefault
tableYes
schemaYes
catalogYes
columnsYes
commentNo
row_estimateNo

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed3 schema fields changedv1.0.0
    • addedInput schema / properties / catalog / description
      Added value: +"Catalog name as list_catalogs shows it. On Pinot it is always `pinot`."
    • addedInput schema / properties / schema / description
      Added value: +"Schema name as list_catalogs shows it. On Pinot a schema is a Pinot database, such as `default`."
    • addedInput schema / properties / table / description
      Added value: +"Table name as list_catalogs shows it."
  2. First observedv0.2.4

TDQS

A4.2/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description still adds genuinely useful behavior: it reads engine metadata and statistics rather than rows, unauthorized tables are refused before the engine is queried, and results are cached for 5 minutes so new columns lag. The remaining gap is minor since the output schema documents the response.

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

Conciseness4/5

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

Front-loaded with the core action and a read-only marker, then layered with prerequisites and caveats. Dense but nearly every clause carries information; the row_estimate and Pinot comment notes are the most verbose portion.

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

Completeness5/5

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

For a three-parameter metadata read with a full output schema, this covers calling preconditions, permission failure, caching staleness, and the semantics of the tricky nullable output fields. An agent can call it correctly and interpret results without further lookup.

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% and each of the three parameters is documented in the schema, including Pinot-specific catalog and schema meaning. The description adds no per-parameter syntax or format detail, so baseline 3 applies.

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?

Opens with a specific verb and resource: 'Get the exact columns and types of one table.' The 'Read-only' clause and the metadata-only framing make it unmistakable versus query_data and list_catalogs.

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

Usage Guidelines5/5

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

Gives an explicit prerequisite ('Always describe a table before querying it; column names you have not seen here are guesses') that binds it to query_data, and routes the missing-table case to list_catalogs. Both when-to-use and the failure fallback are named.

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

Deploy Server

Other Tools