Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With readOnlyHint=true, the safety profile is already provided by annotations. The description adds useful behavioral context by explaining the default list-all behavior when 'regel' is omitted, and by detailing what the explanation contains. There is no contradiction with the read-only annotation.

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 description is a single dense sentence with no filler. It front-loads the main action and examples, then lists the specific aspects of the explanation and the fallback behavior. Every clause contributes useful 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?

For a simple read-only tool with one optional parameter and no output schema, the description is complete. It tells the agent what the tool does, what kinds of rule IDs are valid, what the explanation covers, and what happens without an argument. No important selection or invocation information 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?

The schema already documents the single 'regel' parameter well, including case-insensitivity and an example. The description adds value by clarifying the behavior when the parameter is omitted, which is not expressed in the schema. This goes beyond the high schema coverage baseline.

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 states a specific verb and resource: it explains a rule ID from a validation message, with concrete examples like BR-08 and PEPPOL-EN16931-R053. The optional no-arg behavior is also covered, so the agent understands both modes of the tool. This clearly distinguishes it from all sibling 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?

The description gives a clear context for use: when the agent has a rule ID from a Prüfmeldung and needs a plain-language explanation. It also explains when no rule ID is given, the tool lists all explained rules. It does not explicitly name alternative tools or state when not to use it, but the usage context is unambiguous.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.