get_einvoicing_rules

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so safety is clear. The description adds the return structure but doesn't discuss permissions or rate limits. With annotations handling the core behavioral disclosure, a 3 is appropriate.

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 sentences with no fluff: first states the function and return fields, second lists use cases. Front-loaded with purpose, every word earns its place.

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?

Given the tool has one parameter, clear description, and an output schema (implied by the return field listing), the description is nearly complete. Minor gap: 'European country' in description vs. possibly non-EU, but that's a small detail.

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 clear description for 'country_code'. The tool description doesn't add additional parameter meaning beyond 'for a given European country', which is already implied by the schema. Baseline 3 is correct.

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 returns e-invoicing obligations for a given country, including specific fields like B2G/B2B/B2C mandatory flags, formats, and timeline. It distinguishes from sibling tools (VAT, working days, validation) by focusing on e-invoicing rules.

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 explicitly says 'Use when building invoice generation systems, determining compliance requirements for EU customers, or automating invoice submission workflows.' No explicit when-not-to-use or alternatives, but the context is clear and covers typical use cases.

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