Diagnose database connection pool health by reporting active and idle counts and identifying leaked connections held longer than a configurable threshold.
Diagnose DB connection pools (active/idle counts + leaked connections held > thresholdMs). / 诊断数据库连接池（活跃/空闲数 + 持有超过 thresholdMs 的泄漏连接）。
| Name | Required | Description | Default |
|---|---|---|---|
| report_id | Yes | ||
| thresholdMs | No |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose the core behavior - it counts active/idle connections and flags connections held longer than thresholdMs - but says nothing about whether it is read-only, what permissions or preconditions (loaded report) are needed, or how costly the scan is.
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?
The English sentence is well front-loaded and waste-free, but the full Chinese translation doubles the length without adding information for an agent parsing English, diluting density.
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?
An output schema exists, so return values need not be explained, and the tool is small. Still, for a diagnostic tool with a mandatory report_id and 0% schema coverage, the description should at least identify what the report reference is and whether the operation is a safe read.
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 compensate. It does define thresholdMs semantically (connections held longer than this are treated as leaked), which is real added value, but report_id - the only required parameter - is given no meaning at all beyond its name.
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?
The description pairs a specific verb, 'Diagnose', with a specific resource, 'DB connection pools', and enumerates the output (active/idle counts, leaked connections). No sibling tool covers connection pools, so it is distinct in practice, though the description never explicitly contrasts itself with the other mat_* diagnostic tools.
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 only implied: an agent can infer it should call this when investigating pool exhaustion or leaks, but there is no explicit when-to-use, no prerequisites (e.g. that a parsed report must exist), and no guidance on when mat_leak_suspects or mat_top_consumers would be the better choice.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.