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

Annotations already cover read-only and open-world safety, so the description's added value is the register routing and the returned field set (name, registered office, VAT registration, active status, RO e-Factura register). It does not mention latency, rate limits, or behavior when a tax ID is unknown, so the picture is strong but not complete.

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, zero filler. The lookup scope and register routing come first, the use case second, so the agent gets the essential framing immediately.

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?

With no output schema, the description correctly enumerates what comes back and explains the routing logic for the single parameter. Only failure/not-found behavior and any request cost are left unstated, which is a minor gap for a one-parameter read tool.

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 the schema already gives format examples. The description adds real meaning beyond that by explaining that the ID's jurisdiction determines which register is queried (ANAF vs VIES), which the schema examples alone do not convey.

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 and resource (look up a company by tax ID) and immediately scopes it to public registers, naming ANAF for Romanian CUIs and VIES for other EU VAT numbers. No sibling tool does company resolution, so the differentiation is implicit but unambiguous.

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?

Gives concrete when-to-use cases: populate a client before create_invoice, or vet a supplier. That is clear context that ties it to sibling tools. It stops short of stating when not to use it or what to do if the lookup fails, which keeps it below a 5.

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