Fetch MySQL/MariaDB global variables to inspect server configuration, with optional name-pattern filtering and target selection for troubleshooting and tuning.
[READ] Global variables (SHOW GLOBAL VARIABLES).
Args: pattern: Optional substring to filter variable names (e.g. 'innodb_buffer', 'max_connections'). target: Target name from config; omit for the default.
| Name | Required | Description | Default |
|---|---|---|---|
| target | No | ||
| pattern | No |
Changes observed during successful MCP inspections.
v0.5.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint annotation already carries the safety profile and the description merely restates it as [READ] (consistent, not contradictory). It does not disclose anything the annotation doesn't, such as whether target requires configured connection credentials or what format results take.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two short arg entries with the purpose front-loaded in the first token. No wasted sentences; the examples are the only elaboration and they earn their place given 0% schema coverage.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-required-parameter read tool with no output schema and no annotations beyond readOnlyHint, the description supplies the purpose and both parameter meanings. It stops short of describing anything about returned values or pagination, but that gap is minor here.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description must carry both parameters — and it does, giving concrete substring examples for pattern ('innodb_buffer', 'max_connections') and explaining that target defaults when omitted. The target definition ('Target name from config') is slightly circular but still communicates the default behavior.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb (show/read) and resource (global variables), even mapping to the underlying SQL statement (SHOW GLOBAL VARIABLES). The [READ] tag and 'Global' qualifier implicitly separate it from the write-side sibling set_global_variable, though it never names that alternative.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Usage is implied by the description (inspect server global variables) but there is no explicit when-to-use guidance, no mention of when to prefer overview, show_status, or server_version instead, and no preconditions. Adequate but leaves routing to the agent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.