Filter tools with GCORE_TOOLS

Most AI clients cannot process hundreds of tools simultaneously. The GCORE_TOOLS environment variable controls which tools are exposed by the server, reducing context consumption and improving tool selection accuracy.

Tool filtering overview

Gcore MCP Server provides approximately 720 tools covering the full API surface. Loading all tools consumes significant context window space, leaving less room for conversation. When too many similar tools are available, models may select incorrect tools or produce slower responses due to schema processing overhead. Claude Code handles large tool sets through deferred loading—tool schemas load on demand rather than at startup. Other clients require explicit filtering to function properly.

Filter syntax

The GCORE_TOOLS variable accepts predefined toolset names, wildcard patterns, and exact tool names. These can be combined in a single value separated by commas. Predefined toolsets are named collections of related tools:

GCORE_TOOLS="instances"
GCORE_TOOLS="instances,management"

Wildcard patterns match tools by name prefix using *:

GCORE_TOOLS="cdn.*"
GCORE_TOOLS="cloud.instances.*"
GCORE_TOOLS="dns.records.*"

Exact tool names specify individual tools:

GCORE_TOOLS="cloud.instances.create,cloud.instances.delete"

Mixed configurations combine toolsets and patterns:

GCORE_TOOLS="instances,management,cloud.gpu_baremetal.clusters.*"

Predefined toolsets

Gcore MCP Server includes predefined toolsets that group related operations. Using toolsets simplifies configuration compared to listing individual tools.

Toolset	Description	Included tools
`management`	Account and project operations	Project list, region list, client info
`instances`	Virtual machine operations	Create, delete, start, stop, resize
`baremetal`	Bare metal servers	Create, delete, reinstall, power
`gpu_baremetal`	GPU bare metal clusters	Cluster management, node operations
`gpu_virtual`	GPU virtual clusters	Virtual GPU cluster operations
`networking`	Network resources	Networks, subnets, floating IPs, load balancers
`security`	Security resources	Security groups, SSH keys, secrets
`storage`	Storage resources	Volumes, snapshots, file shares
`ai`	AI clusters	AI cluster management
`ai_ml`	AI/ML inference	Inference deployment, model management
`billing`	Billing information	Cost reports, usage data
`containers`	Container registries	Registry and image management
`cleanup`	Deletion operations	Resource cleanup tools
`list`	Read-only operations	All list/get operations

Pattern matching

Patterns use * as a wildcard to match tool name prefixes. The pattern cdn.* matches all CDN tools including cdn.cdn_resources.list, cdn.cdn_resources.create, and cdn.origins.list. More specific patterns like cdn.cdn_resources.* match only the CDN resource tools, excluding origin and other CDN tools.

Pattern	Matches
`cdn.*`	All CDN tools
`cdn.cdn_resources.*`	CDN resource tools only
`cloud.instances.*`	Cloud instance tools
`cloud.*`	All cloud service tools
`dns.records.create`	Single specific tool
`*`	All tools

Multiple products combine with commas: GCORE_TOOLS="cdn.*,dns.*" exposes all CDN and DNS tools. Nested filtering narrows scope: GCORE_TOOLS="cloud.gpu_baremetal.clusters.*" exposes GPU bare metal cluster tools without including other cloud tools.

Default behavior

When GCORE_TOOLS is not set, the server applies default toolsets based on transport mode. Stdio transport defaults to the management toolset, while HTTP transport defaults to management,instances. These defaults provide minimal tools for basic exploration without overwhelming the client.

Transport	Default tools
stdio	`management` toolset
HTTP	`management,instances` toolsets

Priority and combination

When combining toolsets and patterns, toolset tools are included first, pattern-matched tools are added second, and duplicates are removed. Toolset definitions take precedence over pattern matches. With GCORE_TOOLS="instances,cloud.volumes.*", all instances toolset tools load first, then volume tools from the pattern are added. If the same tool appears in both, it appears once in the final set.

Configuration examples

Use case	Configuration
CDN management	`GCORE_TOOLS="cdn.*"`
DNS management	`GCORE_TOOLS="dns.*"`
Cloud infrastructure	`GCORE_TOOLS="management,instances,storage,networking"`
GPU cluster operations	`GCORE_TOOLS="management,gpu_baremetal"`

Setting GCORE_TOOLS=* exposes all 720 tools. Use this configuration with Claude Code where deferred loading prevents context overflow. Other clients may fail or become unresponsive with this setting.

Verify active tools

After configuring, verify which tools are exposed using MCP Inspector. Connect with the desired GCORE_TOOLS value and view the Tools panel to count and verify the tool list. Server logs also indicate loaded tools at startup. Running GCORE_TOOLS="cdn.*" gcore-mcp-server 2>&1 | head -50 displays startup messages including the tool count.

Patterns are case-sensitive and must match actual tool names. If no tools appear, check the pattern syntax and use MCP Inspector to discover correct tool names. The product prefix matters—cdn differs from cloud in the tool namespace.

​Tool filtering overview

​Filter syntax

​Predefined toolsets

​Pattern matching

​Default behavior

​Priority and combination

​Configuration examples

​Verify active tools

Tool filtering overview

Filter syntax

Predefined toolsets

Pattern matching

Default behavior

Priority and combination

Configuration examples

Verify active tools