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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description usefully adds what the response will contain (meaning, usual causes, fix, and who is responsible for the fix), which is behavioral context beyond the annotations.

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 dense sentence with the purpose front-loaded and examples placed immediately after the resource, so the format hint arrives before any schema lookup is needed. No filler.

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 spelled out, and the description still previews the four content sections of the answer. Complete enough for a one-parameter lookup tool; the only missing piece is guidance on invalid or unknown codes.

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 0% for the single required 'code' parameter, so the description carries the burden — and it does supply concrete example values that convey the expected code format. It stops short of stating the accepted code systems, case sensitivity, or behavior on an unrecognized code.

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 ('explain') and a specific resource (an e-invoice validation rule code), and even names the standard families the codes come from ('BR-CO-10', 'PEPPOL-EN16931-R120'). No sibling tool ('deadlines', 'providers', 'lookup_access_point') could be mistaken for this one.

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 it has a validation error code in hand, but the description never says when to use it versus other routes, nor what to do if the code is unknown or unrecognized.

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