Retrieve the reasoning behind any detection rule: what it flags, why it matters, which audit it came from, and what it ignores. Read-only and offline.
Return the reasoning behind one of the seven rules: what it detects, why it matters, the audit it came from, and what it deliberately does not fire on. Offline and read-only.
| Name | Required | Description | Default |
|---|---|---|---|
| rule | Yes | The rule identifier, as it appears in findings. |
Changes observed during successful MCP inspections.
v0.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false, and destructiveHint=false, so 'Offline and read-only' is largely redundant. The genuinely additive behavior detail is that the output includes what the rule 'deliberately does not fire on', disclosing a false-positive scope, but no other behavioral context (no traceability to the findings schema, no guarantee of stability) is offered.
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 tight sentences with the content of the return value front-loaded. The trailing 'Offline and read-only' clause is minor padding since annotations already carry that information.
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?
There is no output schema, so the description correctly compensates by enumerating the four components of the response. Combined with a fully documented single enum parameter, an agent has enough to invoke it correctly; only explicit usage/selection guidance is missing.
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 coverage is 100% and the enum itself lists all seven rule identifiers, so the schema does the heavy lifting. The description only echoes 'one of the seven rules', adding no syntax, casing, or selection guidance beyond the enum.
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 (return the reasoning) and resource (one of the seven rules), and enumerates the exact content returned: detection target, rationale, originating audit, and non-firing cases. This clearly distinguishes it from the scan_* siblings, which produce findings rather than explain them.
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 rather than stated: an agent should infer this is used to interpret a rule id appearing in findings. There is no explicit when-to-use framing, no mention of what alternative to use if the rule id is unknown or if raw rule definitions are wanted.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.