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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered structurally. The description adds real context beyond that: it names the returned content categories (price composition, price-guarantee scope, renewal/cancellation terms, deposit, energy mix, ratings) and flags the eco-tariff special case. It does not discuss rate limits or error behavior, so not a 5.

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 purpose and scope are front-loaded in the first clause, and the field enumeration is compact. The trailing keyword block (German and English synonyms) is padding for search matching rather than agent guidance, which costs it a point.

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 explained, yet the description still summarizes them; combined with full annotation and parameter coverage, an agent has what it needs to call it correctly. Only minor routing detail (when not to call it, or how it pairs with book-contract/start-booking) is absent.

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?

With 100% schema description coverage, the schema already documents both `ref` (pattern, origin) and `language` (enum, default). The description's note that "texts come in the requested language" loosely reinforces the schema's narrower statement that language applies to the eco statement/proof texts – marginal added value, so the baseline 3 applies.

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 ("Returns the full conditions of one tariff") and pins the source ("from a compare-tariffs result, identified by its ref"), which cleanly separates it from the sibling compare-tariffs lister. It even enumerates the condition categories returned, so an agent knows exactly what this yields.

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 makes the workflow dependency explicit: the ref must come from a compare-tariffs result, which tells the agent when this tool is callable. It gives no explicit exclusions or routing between further siblings (e.g., book-contract vs. tariff-details), so it stops just short of full when/when-not guidance.

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