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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description adds material context beyond them: everything past the first 8 characters is discarded by the backend and never stored, logged, or forwarded, and NOT_FOUND carries a specific meaning (the value belongs to no Austrian operator, i.e. a typo) that must be conveyed to the user verbatim rather than left vague.

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 critical constraint (first 8 characters only, never solicit) is front-loaded, and each sentence targets a distinct failure mode. It is verbose and repeats the 8-character rule several times in heavy caps, which costs some economy, but the redundancy is defensible for an unusual edge-case-heavy contract.

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 an output schema present, return-value documentation is optional, yet the description still sketches the result (operator name). Combined with the truncation rule and the NOT_FOUND interpretation, an agent has everything needed to call and interpret this read-only tool correctly.

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%, so the schema already documents the parameter, and the description largely restates the 8-vs-33 character rule. It does add the operative instruction to truncate on the agent's behalf and never send more than 8 characters, which goes slightly beyond the schema's passive constraint statement.

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 the network operator for a Zählpunkt prefix) and anchors it with a concrete example (AT001000 → Wiener Netze). The sibling tools (tariffs, consumption, switching) are unrelated domains, so no disambiguation is needed, and the tool is unmistakable.

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?

Explicit when-to-use and when-not-to-use: only call when the user volunteers the Zählpunktbezeichnung unprompted, and never solicit the field. It also pre-empts the wrong behavior of rejecting a value or asking for the 'full 33-digit' identifier, which is exactly the alternative action an agent might otherwise take.

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