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

Annotations already cover safety (readOnlyHint, idempotentHint, openWorldHint=false), so the bar is lower. The description still adds real behavioral context the annotations don't carry: source ordering (most binding first), what accompanies each rule (date, validity period, source link), parent-code inheritance (8-98f → 8-98f.20), and the 'anwendbarkeit' semantics returned when 'aufnahmedatum' is supplied.

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?

A single dense paragraph, front-loaded with the payoff (what is returned and in what order), followed by the inheritance rule and the applicability note. Every sentence is informative, though the final sentence about 'anwendbarkeit' is tightly packed and reads as a run-on.

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 and annotations carry the safety profile, so the description need not explain return values — yet it still characterizes the result shape (per-rule date, validity, source link). Combined with the inheritance and applicability behavior, an agent has enough to call this correctly; only explicit sibling routing is missing.

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 description coverage is 100%, so the schema already documents all five parameters including code normalization, katalog auto-detection, and the interaction constraints (year only without 'aufnahmedatum'; 'pruefungAm' only with 'aufnahmedatum'). The description restates the applicability behavior linked to 'aufnahmedatum' but adds no parameter detail beyond the schema, 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 concrete verb ("Liefert") and a precise resource: all rules outside the catalog affecting an ICD/OPS/DRG code, naming the three sources (DKR, Schlichtungsausschuss §19 KHG, SEG-4). This scope phrase distinguishes it from catalog tools like dkr_get and seg4kde_get, but the description never explicitly contrasts it with the sibling rules_get, so the differentiation is by scope rather than by naming an alternative.

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?

Usage is only implied: the agent can infer this tool is for looking up code-linked regulations, and the description explains how 'aufnahmedatum' changes applicability output. There is no explicit when-to-use/when-not statement and no routing to alternatives such as rules_get or seg4kde_search, leaving the agent to infer the choice.

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