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mcp-clickhousex

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Python
Remote

Herramienta MCP ClickHouse

CI PyPI Python 3.13+ License: MIT

Un servidor de solo lectura del Model Context Protocol (MCP) para ClickHouse que admite descubrimiento de metadatos, recursos, consultas SELECT parametrizadas, introspección SHOW, análisis de consultas y modo de instantánea para conjuntos de resultados grandes, con configuración basada en perfiles y aplicación estricta de no-DML/DDL.

Requisitos: Python 3.13+, una instancia de ClickHouse en ejecución y detalles de conexión mediante variables de entorno o un archivo de configuración.

Inicio rápido

Establezca un DSN y ejecute el servidor con MCP Inspector:

# Option 1: Run directly with uvx (no clone needed)
export MCP_CLICKHOUSE_DSN="http://default:@localhost:8123/default"
npx -y @modelcontextprotocol/inspector uvx mcp-clickhousex
# Option 2: Run from source (clone repo, then)
export MCP_CLICKHOUSE_DSN="http://default:@localhost:8123/default"
npx -y @modelcontextprotocol/inspector uv run main.py

Related MCP server: io.github.Aguantar/clickhouse-dataops-mcp

Configuración

Todos los ajustes usan el prefijo MCP_CLICKHOUSE. Las variables de entorno planas (p. ej. MCP_CLICKHOUSE_DSN) son la forma directa de configurar el perfil predeterminado cuando se tiene una única conexión. Para varios perfiles, se recomienda el archivo config.json con ámbito de usuario.

Conexión única: configúrela mediante variables de entorno.

# Connection DSN (required).
export MCP_CLICKHOUSE_DSN="http://user:password@host:8123/database"

# Optional description for the default profile (tooling/AI discovery).
export MCP_CLICKHOUSE_DESCRIPTION="Primary cluster"

# Optional max rows per interactive query (default 500; hard ceiling 1000).
export MCP_CLICKHOUSE_QUERY_MAX_ROWS="500"

# Optional interactive query timeout in seconds (default 30; hard ceiling 300).
export MCP_CLICKHOUSE_QUERY_COMMAND_TIMEOUT_SECONDS="30"

# Optional max rows for snapshot queries (default 10000; hard ceiling 50000).
export MCP_CLICKHOUSE_SNAPSHOT_MAX_ROWS="10000"

# Optional snapshot query timeout in seconds (default 120; hard ceiling 300).
export MCP_CLICKHOUSE_SNAPSHOT_COMMAND_TIMEOUT_SECONDS="120"

Conexiones múltiples: use el archivo config.json con ámbito de usuario (recomendado). Las variables de entorno también funcionan mediante el prefijo MCP_CLICKHOUSE_PROFILES_<NAME>_ (p. ej. MCP_CLICKHOUSE_PROFILES_WAREHOUSE_DSN).

  • Unix-like: ~/.config/mcp-clickhousex/config.json

  • Windows: %USERPROFILE%\.config\mcp-clickhousex\config.json

Ejemplo (config.json):

{
  "profiles": {
    "default": {
      "dsn": "http://default:@localhost:8123/default",
      "description": "Primary",
      "query_max_rows": 500,
      "query_command_timeout_seconds": 60,
      "snapshot_max_rows": 10000,
      "snapshot_command_timeout_seconds": 120
    },
    "warehouse": {
      "dsn": "http://user:pass@warehouse:8123/analytics",
      "description": "Warehouse"
    }
  }
}

Caracteres especiales en las credenciales: si el nombre de usuario o la contraseña contienen caracteres reservados de URL, codifíquelos con porcentaje en el DSN:

Carácter

Codificación

#

%23

?

%3F

/

%2F

@

%40

%

%25

Por ejemplo, el nombre de usuario admin@org y la contraseña p#ss? se convierten en admin%40org:p%23ss%3F en el DSN: http://admin%40org:p%23ss%3F@host:8123/database.

Herramientas

Las descripciones de las herramientas coinciden con los docstrings de las herramientas de server.py, excepto que el prefijo [ClickHouse] se omite aquí (permanece en los metadatos expuestos por MCP). El texto de los parámetros coincide con cada Field(description=…) de la misma herramienta.

Herramienta

Descripción

Parámetros clave

list_profiles

Lista los perfiles configurados. Cada entrada incluye nombre y descripción opcional.

—

get_cluster_properties

Obtiene las propiedades del clúster y los límites de ejecución. Devuelve la versión del servidor ClickHouse más los límites aplicados (máx. filas, tiempos de espera) para el perfil.

profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles.

run_query

Ejecuta SELECT de solo lectura o WITH … SELECT. Una sola sentencia; se rechazan DML, DDL, SET, SYSTEM y similares. Devuelve {data, row_count} donde data es una cadena CSV RFC 4180. Pasa snapshot=true para persistir el resultado en disco y recibir {snapshot_uri, row_count} en su lugar; obtén el CSV mediante el URI de recurso de snapshot. Límite máximo de filas; el desbordamiento establece truncated y row_limit. Misma validación SQL que analyze_query.

sql (obligatorio) — SELECT de solo lectura o WITH … SELECT. Una sola sentencia; usa db.table o database calificados. Sintaxis de marcador de posición del driver para parámetros. parameters — Parámetros con nombre para marcadores de posición del driver (p. ej. %(name)s o {name:Type}). database — Base de datos predeterminada de la sesión para nombres no calificados. Fuente: databases. profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles. snapshot — Cuando es true, persiste el resultado completo como archivo CSV y devuelve un URI de recurso (chx://snapshots/{id}) en lugar de datos en línea. Úsalo para consultas que puedan superar el límite interactivo de filas (1 000). Se aplican límites de snapshot (predeterminado 10 000 filas, tope máximo 50 000). Las entradas caducan a los 7 días.

run_show

Ejecuta una sentencia de introspección SHOW. Una sentencia por llamada; se rechaza INTO OUTFILE. Se aplican límites interactivos de filas (predeterminado 500, tope máximo 1 000). Mismo tiempo de espera que run_query.

sql (obligatorio) — Una sola sentencia SHOW (p. ej. SHOW DATABASES, SHOW CREATE TABLE). Sin INTO OUTFILE. parameters — Parámetros con nombre para marcadores de posición del driver (p. ej. %(name)s o {name:Type}). database — Base de datos predeterminada de la sesión para nombres no calificados. Fuente: databases. profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles.

analyze_query

Explica SELECT de solo lectura o WITH … SELECT. Devuelve texto de plan, pipeline y/o sintaxis. Tipos predeterminados: plan y pipeline. Usa el tiempo de espera de consulta y base de datos opcional; sin límite máximo de filas a diferencia de run_query.

sql (obligatorio) — SELECT de solo lectura o WITH … SELECT para EXPLAIN. Una sola sentencia; misma validación que run_query. parameters — Parámetros con nombre para marcadores de posición del driver (p. ej. %(name)s o {name:Type}). database — Base de datos predeterminada de la sesión para nombres no calificados. Fuente: databases. profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles. types — Variantes de EXPLAIN: plan (índices), pipeline, syntax. Predeterminado: plan y pipeline si se omite.

list_databases

Lista las bases de datos. Filas de system.databases visibles para la conexión.

profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles.

list_tables

Lista tablas y vistas en una base de datos. Filas de system.tables: name, engine, primary_key, sorting_key, partition_key, total_rows, total_bytes para la planificación de consultas.

database — Base de datos a listar; predeterminada del cliente si se omite. Fuente: databases. profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles.

list_columns

Lista columnas de una tabla o vista. Filas de system.columns para la base de datos y tabla resueltas.

table (obligatorio) — Nombre de tabla o vista, o database.table. Fuente: tables. database — Base de datos cuando table no está calificada; se ignora si table contiene un punto. Predeterminada del cliente si se omite. Fuente: databases. profile — Nombre del perfil; usa el perfil predeterminado si se omite. Fuente: profiles.

Recursos

El servidor expone el mismo descubrimiento y metadatos que las herramientas anteriores a través de recursos direccionables por URI (jerarquía primero-perfil). La description de cada recurso coincide con la herramienta correspondiente (list_profiles, get_cluster_properties, list_databases, list_tables, list_columns), más etiquetas Src: para los parámetros de ruta URI. Todo el contenido de los recursos es JSON (application/json) excepto las instantáneas que devuelven CSV (text/csv). Use el segmento de ruta default para el perfil o base de datos predeterminado.

Las descripciones de los recursos coinciden con description=… en @mcp.resource en server.py (misma omisión de prefijo que arriba).

URI

Descripción

chx://profiles

Lista los perfiles configurados. Cada entrada incluye nombre y descripción opcional.

chx://profiles/{profile}/cluster-properties

Obtiene las propiedades del clúster y los límites de ejecución. Devuelve la versión del servidor ClickHouse más los límites aplicados (máximo de filas, tiempos de espera) para el perfil. Src: profiles.

chx://profiles/{profile}/databases

Lista las bases de datos. Filas de system.databases visibles para la conexión. Src: profiles.

chx://profiles/{profile}/databases/{database}/tables

Lista tablas y vistas en una base de datos. Filas de system.tables: name, engine, primary_key, sorting_key, partition_key, total_rows, total_bytes para la planificación de consultas. Src: profiles, dbs.

chx://profiles/{profile}/databases/{database}/tables/{table}/columns

Lista las columnas de una tabla o vista. Filas de system.columns para la base de datos y tabla resueltas. Src: profiles, dbs, tables.

chx://snapshots/{id}

Obtiene una instantánea del resultado de una consulta por ID. Devuelve el resultado completo como una cadena CSV (fila de encabezado + filas de datos). Las entradas caducan después de 7 días. Src: run_query con snapshot=true.

Seguridad

Solo SQL de solo lectura: run_query permite SELECT / WITH … SELECT; run_show permite una única sentencia SHOW por llamada. INTO OUTFILE no está permitido en run_show. Las consultas interactivas imponen un límite estricto de filas (predeterminado 500, tope máximo 1 000); para extracciones más grandes use snapshot=true (predeterminado 10 000, tope máximo 50 000). Se admiten consultas parametrizadas donde el controlador lo permite (sintaxis %(name)s o {name:Type}). Use variables de entorno para las credenciales de conexión — nunca comprometa secretos.

Ejemplos de host MCP

Fragmentos para clientes MCP comunes usando uvx mcp-clickhousex (no se requiere clonar; asegúrese de que uv esté en su PATH). Reemplace los detalles de conexión según sea necesario.

Cursor

{
  "mcpServers": {
    "clickhouse": {
      "command": "uvx",
      "args": ["mcp-clickhousex"],
      "env": {
        "MCP_CLICKHOUSE_DSN": "http://default:@localhost:8123/default"
      }
    }
  }
}

Codex

[mcp_servers.clickhouse]
command = "uvx"
args = ["mcp-clickhousex"]

[mcp_servers.clickhouse.env]
MCP_CLICKHOUSE_DSN = "http://default:@localhost:8123/default"

OpenCode

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "clickhouse": {
      "type": "local",
      "enabled": true,
      "command": ["uvx", "mcp-clickhousex"],
      "environment": {
        "MCP_CLICKHOUSE_DSN": "http://default:@localhost:8123/default"
      }
    }
  }
}

Claude Code

{
  "mcpServers": {
    "clickhouse": {
      "command": "uvx",
      "args": ["mcp-clickhousex"],
      "env": {
        "MCP_CLICKHOUSE_DSN": "http://default:@localhost:8123/default"
      }
    }
  }
}

Copilot

{
  "inputs": [],
  "servers": {
    "clickhouse": {
      "type": "stdio",
      "command": "uvx",
      "args": ["mcp-clickhousex"],
      "env": {
        "MCP_CLICKHOUSE_DSN": "http://default:@localhost:8123/default"
      }
    }
  }
}

Ubicaciones de archivos de configuración: Cursor .cursor/mcp.json, Codex/Copilot/OpenCode varían según el cliente; consulte la documentación MCP de su cliente.

Pruebas

Las pruebas requieren una instancia de ClickHouse en ejecución. El conjunto de pruebas crea una tabla de muestra en la base de datos predeterminada, la llena y la elimina después.

# Run all tests (unit + functional + e2e)
uv run pytest tests/ -v

El arnés de pruebas usa MCP_TEST_CLICKHOUSE_DSN para localizar la instancia de ClickHouse. Si no está configurado, recurre a http://admin:password123@localhost:8123/default. Configure la variable para apuntar las pruebas a un servidor diferente sin afectar su MCP_CLICKHOUSE_DSN de producción:

export MCP_TEST_CLICKHOUSE_DSN="http://user:pass@testhost:8123/default"
uv run pytest tests/ -v

Hoja de ruta

No hay funciones planificadas en este momento. Abra un issue para sugerir mejoras.

Contribuciones

Abra issues o PRs; siga el estilo existente y agregue pruebas donde corresponda.

Licencia

MIT. Consulte LICENSE.

Available Tools

8 tools
analyze_queryA
Read-only

[ClickHouse] Explain read-only SELECT or WITH … SELECT.

Returns plan, pipeline, and/or syntax text. Default types plan and pipeline. Uses query timeout and optional database; no max-rows cap unlike run_query.

ParametersJSON Schema
NameRequiredDescriptionDefault
sqlYesRead-only SELECT or WITH … SELECT for EXPLAIN. One statement; same validation as run_query.
typesNoEXPLAIN variants: plan (indexes), pipeline, syntax. Default plan and pipeline if omitted.
profileNoProfile name; uses default profile when omitted. Src: profiles.
databaseNoSession default database for unqualified names. Src: databases.
parametersNoNamed parameters for driver placeholders (e.g. %(name)s or {name:Type}).

Output Schema

ParametersJSON Schema
NameRequiredDescription
planNoEXPLAIN PLAN output.
syntaxNoEXPLAIN SYNTAX output.
pipelineNoEXPLAIN PIPELINE output.

TDQS

A4.6/5.0
Behavior5/5

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

Description adds behavioral context beyond readOnlyHint and openWorldHint annotations, such as query timeout, optional database, and the absence of max-rows cap. No contradiction.

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?

Three concise sentences, front-loaded with core purpose, and each sentence provides distinct information without redundancy.

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 output schema existence and high parameter coverage, description covers key aspects: purpose, defaults, and comparison. Minor missing details like timeout value are acceptable.

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

Parameters4/5

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

Schema coverage is 100%, but description adds value by specifying default types (plan and pipeline) and mentioning query timeout, which is not in schema. Slight improvement over baseline.

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?

Description clearly states the tool performs EXPLAIN on read-only SELECT/WITH SELECT, returning plan/pipeline/syntax. Distinguishes from sibling run_query by noting no max-rows cap.

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

Usage Guidelines4/5

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

Provides context on when to use (for EXPLAIN) and comparison to run_query. Implicitly limits to read-only queries but lacks explicit alternatives for DDL or other analysis tools.

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

get_cluster_propertiesA
Read-only

[ClickHouse] Get cluster properties and execution limits.

Returns ClickHouse server version plus enforced limits (max rows, timeouts) for the profile.

ParametersJSON Schema
NameRequiredDescriptionDefault
profileNoProfile name; uses default profile when omitted. Src: profiles.

Output Schema

ParametersJSON Schema
NameRequiredDescription
limitsYes
versionYesClickHouse server version string.

TDQS

A4.1/5.0
Behavior4/5

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

Annotations already indicate readOnlyHint=true, and the description adds context about specific returned data (version, limits). No contradiction. Does not mention any side effects or authorization needs, but read-only nature covers safety.

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?

Two sentences, no fluff. First sentence states purpose, second describes output. Information is front-loaded and every sentence adds value.

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?

With an output schema present and simple input, the description provides all necessary context. Annotations cover safety, and the description adequately explains the tool's scope and return content.

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 coverage is 100% and describes the profile parameter well. The description does not add extra details beyond the schema, which is adequate for a single optional parameter.

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?

Description clearly states 'Get cluster properties and execution limits' and specifies it returns 'ClickHouse server version plus enforced limits', which is a specific verb and resource. It distinguishes from sibling tools like run_query and list_profiles.

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?

Implied usage as a read-only check for server properties and limits, but no explicit when-to-use or when-not-to-use guidance compared to siblings like list_profiles.

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

list_columnsA
Read-only

[ClickHouse] List columns for a table or view.

Rows from system.columns for the resolved database and table.

ParametersJSON Schema
NameRequiredDescriptionDefault
tableYesTable or view name, or database.table. Src: tables.
profileNoProfile name; uses default profile when omitted. Src: profiles.
databaseNoDatabase when table is unqualified; ignored if table contains a dot. Client default when omitted. Src: databases.

Output Schema

ParametersJSON Schema
NameRequiredDescription
rowsYesRow values aligned with the columns list.
columnsYesOrdered list of column names. Each row aligns with these names by index.

TDQS

A3.9/5.0
Behavior3/5

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

Annotations already indicate readOnlyHint=true, so the description's mention of using system.columns adds some context but does not reveal additional behavioral traits beyond what annotations provide.

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 extremely concise with just two sentences, no redundancy, and the key purpose is front-loaded. Every word adds value.

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 simple read-only list tool with full parameter documentation, an output schema, and clear annotations, the description sufficiently covers the context and functionality without needing to explain return values.

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 the tool description does not add any extra meaning beyond the existing parameter descriptions, such as explaining the 'Src' references or providing examples.

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 'List columns for a table or view' with a specific verb and resource. It includes the context '[ClickHouse]' and mentions the data source 'Rows from system.columns', making it distinct from sibling tools like list_tables or list_databases.

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 implies usage for listing columns of a table or view, but it does not provide explicit guidance on when to use this tool vs alternatives, nor does it mention any prerequisites or exclusions.

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

list_databasesB
Read-only

[ClickHouse] List databases.

Rows from system.databases visible to the connection.

ParametersJSON Schema
NameRequiredDescriptionDefault
profileNoProfile name; uses default profile when omitted. Src: profiles.

Output Schema

ParametersJSON Schema
NameRequiredDescription
rowsYesRow values aligned with the columns list.
columnsYesOrdered list of column names. Each row aligns with these names by index.

TDQS

B3.4/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true. Description adds the detail that it queries system.databases and depends on connection visibility. No contradictions with annotations.

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?

Two concise sentences, no wasted words, front-loaded with purpose and context.

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?

For a simple read-only tool with one optional parameter and an output schema, the description is adequate. Provides source table and visibility context, but could mention output shape briefly.

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 coverage is 100% with parameter 'profile' already documented. Description adds no extra meaning beyond the schema.

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?

Clearly states verb 'List' and resource 'databases', includes context '[ClickHouse]' and source 'system.databases'. Differentiates from siblings like 'list_tables' implicitly but no explicit distinction.

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?

Mentions that rows are from system.databases and visible to the connection, but provides no guidance on when to use this tool vs alternatives like list_tables or run_show. Lacks explicit when-to-use or when-not-to-use.

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

list_profilesA
Read-only

[ClickHouse] List configured profiles.

Each entry includes name and optional description.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A3.5/5.0
Behavior3/5

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

The description adds value beyond annotations by specifying that output includes name and optional description. Annotations already declare readOnlyHint=true, so the read-only nature is known. No additional behavioral traits (e.g., ordering, filtering) are disclosed, but the description does not contradict annotations.

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 extremely concise: two sentences that front-load the purpose and follow with a key output detail. Every word earns its place with no redundancy or fluff.

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 zero parameters and the presence of an output schema, the description is mostly complete. It explains what the tool does and what output to expect. It could optionally mention the source of profiles (e.g., system.profiles), but the current level is adequate for a simple listing tool.

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

Parameters4/5

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

The input schema has no parameters, so schema description coverage is 100%. The description does not need to add parameter semantics. It provides a baseline adequate for a parameterless tool.

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 clearly states the action ('List configured profiles') and the resource ('profiles'). The output details are mentioned (name and optional description). However, it does not explicitly differentiate from sibling list tools (e.g., list_databases, list_tables) beyond the resource name, lacking a contrastive statement.

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?

No guidance is provided on when to use this tool versus alternatives. There is no mention of prerequisites, common use cases, or when not to use it. The tool is simple, but the description does not help an agent decide between this and other list tools.

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

list_tablesA
Read-only

[ClickHouse] List tables and views in a database.

Rows from system.tables: name, engine, primary_key, sorting_key, partition_key, total_rows, total_bytes for query planning.

ParametersJSON Schema
NameRequiredDescriptionDefault
profileNoProfile name; uses default profile when omitted. Src: profiles.
databaseNoDatabase to list; client default when omitted. Src: databases.

Output Schema

ParametersJSON Schema
NameRequiredDescription
rowsYesRow values aligned with the columns list.
columnsYesOrdered list of column names. Each row aligns with these names by index.

TDQS

A3.6/5.0
Behavior3/5

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

Annotations already declare readOnlyHint=true, and the description adds context about the specific columns returned. However, it does not disclose any behavioral traits beyond that, but given the annotations, this is adequate.

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?

Extremely concise: two sentences that front-load the purpose and return value. No unnecessary words or repetition.

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?

For a simple read-only list tool with an output schema and well-documented parameters, the description is nearly complete. A minor gap: it does not clarify behavior when database is omitted (client default), but overall it is sufficient.

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 the schema already documents both parameters (profile, database). The description does not add extra meaning beyond what the schema provides, meeting the baseline.

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 lists tables and views in a database, specifying the source (system.tables) and the columns returned. It effectively distinguishes from sibling tools like list_databases and list_columns by focusing on tables.

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?

No guidance on when to use this tool versus alternatives (e.g., run_show or analyze_query). The description merely states functionality without providing context on preferred scenarios or limitations.

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

run_queryA
Read-only

[ClickHouse] Execute read-only SELECT or WITH … SELECT.

One statement; DML, DDL, SET, SYSTEM, and similar are rejected. Max-rows cap; overflow sets truncated and row_limit. Same SQL validation as analyze_query.

Returns {data, row_count} where data is an RFC 4180 CSV string. Pass snapshot=true to persist the result to disk and receive a {snapshot_uri, row_count} instead; fetch the CSV via the snapshot resource URI.

ParametersJSON Schema
NameRequiredDescriptionDefault
sqlYesRead-only SELECT or WITH … SELECT. One statement; use qualified db.table or database. Driver placeholder syntax for parameters.
profileNoProfile name; uses default profile when omitted. Src: profiles.
databaseNoSession default database for unqualified names. Src: databases.
snapshotNoWhen true, persist the full result as a CSV file and return a resource URI (chx://snapshots/{id}) instead of inline data. Use for queries that may exceed the interactive row limit (1 000). Snapshot limits apply (default 10 000 rows, hard ceiling 50 000). Entries expire after 7 days.
parametersNoNamed parameters for driver placeholders (e.g. %(name)s or {name:Type}).

Output Schema

ParametersJSON Schema
NameRequiredDescription
resultYes

TDQS

A4.7/5.0
Behavior5/5

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

Annotations declare readOnlyHint=true and openWorldHint=true. Description aligns fully and adds rich behavioral details: max-rows cap, truncation with row_limit flag, CSV return format, snapshot persistence with expiration and limits. No contradictions.

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?

Description is a single, well-structured paragraph with each sentence serving a distinct purpose: resource and verb, constraints, limits, return format, and snapshot alternative. No fluff.

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 tool with 5 parameters, 100% schema coverage, and an output schema (not shown but indicated), the description covers purpose, constraints, limits, return format, and snapshot behavior comprehensively. No gaps given the context.

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

Parameters4/5

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

Input schema has 100% description coverage, but description adds value by explaining the return format (CSV string and snapshot URI pattern) which is not in the input schema. Also reiterates constraints on sql parameter. Overall meaningfully supplements schema.

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?

Description clearly states it executes read-only SELECT or WITH SELECT on ClickHouse. It specifies the resource ([ClickHouse] queries) and verb (execute read-only). Distinguishes from siblings like run_show and analyze_query by stating specific SQL types and validation.

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

Usage Guidelines4/5

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

Explicitly states that only read-only queries are allowed, and DML/DDL/SET etc. are rejected. Mentions same validation as analyze_query, linking to a sibling. Clear context for when to use, but does not explicitly exclude alternatives or provide when-not-to-use guidance.

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

run_showA
Read-only

[ClickHouse] Execute SHOW introspection statement.

One statement per call; INTO OUTFILE rejected. Interactive row limits apply (default 500, hard ceiling 1 000). Same timeout as run_query.

ParametersJSON Schema
NameRequiredDescriptionDefault
sqlYesSingle SHOW statement (e.g. SHOW DATABASES, SHOW CREATE TABLE). No INTO OUTFILE.
profileNoProfile name; uses default profile when omitted. Src: profiles.
databaseNoSession default database for unqualified names. Src: databases.
parametersNoNamed parameters for driver placeholders (e.g. %(name)s or {name:Type}).

Output Schema

ParametersJSON Schema
NameRequiredDescription
rowsYesRow values aligned with the columns list.
columnsYesOrdered list of column names. Each row aligns with these names by index.
row_limitNoThe enforced maximum number of rows returned for this query.
truncatedNoWhether the result set was truncated due to the enforced row limit.

TDQS

A4.7/5.0
Behavior5/5

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

Annotations already mark as read-only, and the description adds critical behavioral details: row limits (500 default, 1000 hard ceiling), INTO OUTFILE rejection, and timeout alignment with run_query. No contradictions.

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?

Three sentences, each earning its place: purpose, constraints on statement, limits. Front-loaded and efficient with zero redundancy.

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?

Given the presence of an output schema, the description sufficiently covers all behavioral aspects for a read-only introspection tool. Includes limits, timeout, and statement restrictions.

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

Parameters4/5

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

Schema coverage is 100%, so baseline is 3. Description adds value by explaining the sql parameter constraint (single statement, no INTO OUTFILE) and implicitly relates to row limits. Modest but helpful addition.

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 it executes SHOW introspection statements, distinguishing from siblings like run_query. It specifies constraints (single statement, no INTO OUTFILE), making the purpose specific and unambiguous.

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

Usage Guidelines4/5

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

Provides clear context for when to use (SHOW statements) and constraints (row limits, timeout). Lacks explicit when-not-to-use alternatives, but the sibling tool names imply run_query for other queries.

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

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 8 tool updatesv0.8.0
    • First observedanalyze_query
    • First observedget_cluster_properties
    • First observedlist_columns
    • First observedlist_databases
    • First observedlist_profiles
    • First observedlist_tables
    • First observedrun_query
    • First observedrun_show
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TDQS

A4/5.0

Scored across 8 tools

Disambiguation5/5

Each tool has a distinct purpose: listing profiles, cluster properties, running SELECT queries, running SHOW statements, analyzing queries, and listing databases, tables, and columns. No overlap in functionality.

Naming Consistency4/5

Uses snake_case consistently, but mixes verb prefixes: 'list_', 'get_', 'run_', 'analyze_'. The pattern is somewhat predictable within categories (metadata listing uses 'list_', execution uses 'run_'), but not fully uniform.

Tool Count5/5

8 tools is well-scoped for a read-only ClickHouse client. Covers metadata discovery, query execution, and analysis without unnecessary tools.

Completeness4/5

Covers essential read-only operations: metadata listing, SELECT, SHOW, and EXPLAIN. Lacks DDL/DML support, but that is intentional. Minor gap: no tool to retrieve table DDL or status.

Maintenance

ActivityMaintained
ResponsivenessNo issues

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