explain_error_code

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

With no annotations, the description carries the burden. It discloses offline operation and no API key requirement, which is valuable. However, it does not mention behavior on unknown error codes or rate limits, which would improve transparency for a read-only tool.

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, well-structured sentence. Every word adds value: explains action, gives examples, states offline/no-key. No unnecessary 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 tool with one parameter and no output schema, the description is nearly complete. It describes the output (plain English, fix, example) and usage context. Minor gap: it doesn't explicitly state that the output is text, but that's implied.

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% with a single parameter. The description adds value by providing concrete examples (00400, BR-DE-21) and clarifying the parameter is for a single code. This goes beyond the schema's dry definition.

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 clearly states the tool's purpose: explain a single e-invoice validation error code in plain English with fix and example. It distinguishes itself from siblings (list_formats, validate_einvoice) by focusing on error code explanation.

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?

No explicit when-to-use or when-not-to-use guidance. Usage is implied (after validation errors), but no alternatives or exclusions are mentioned. The context from sibling tools makes it understandable but the description does not provide direct guidance.

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