explain_ruleExplains a specific MCP Guard Scan rule by showing what it detects, bad and good examples, remediation steps, and references so you can understand and fix findings.
Explain one rule, e.g. MCPG-002: what it detects, a bad and a good example, how to fix it and references.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Rule id, e.g. MCPG-002. |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by disclosing the shape of the response: what the rule detects, a bad and a good example, remediation steps, and references. With no output schema present, this return-content preview is the main behavioral payload.
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?
One sentence, front-loaded with the verb and resource, and the enumeration of return contents is compact. Slightly run-on, but no sentence is wasted.
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 one-parameter read tool with no output schema, the description covers purpose and the contents of the returned explanation well enough to call it correctly. The only real gap is not telling the agent where rule ids come from or what happens for an unknown id.
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 there is a single required parameter already documented as "Rule id, e.g. MCPG-002". The description's example repeats the schema's example verbatim and adds no format, casing, or lookup guidance beyond it, so baseline 3 applies.
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?
"Explain one rule" gives a specific verb and resource, and the example id (MCPG-002) makes the unit of work concrete. It is distinguishable in practice from list_rules, but the description never names that sibling or states the single-rule scope as an explicit contrast.
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 this is the follow-up to list_rules or scan_server when it needs detail on a specific rule id. There is no explicit when-to-use statement, no mention of where rule ids come from, and no exclusion of alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.