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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds genuine behavioral context beyond them: the target range is only present 'wo die Seite einen nennt', high/low values are hedged as what they 'KÖNNEN' mean, and it instructs the agent to always note that the range on the user's own lab report applies.

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?

Purpose is front-loaded, then a compact example, then a short Args block. The return-field list is dense but earns its place since it defines scope. Slightly long for the value delivered, but no filler sentences.

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 values need not be described, and the safety annotations cover the write/read profile. The description supplies the remaining decision-relevant context (what a marker lookup yields, the interpretation caveat), leaving only pagination/error behavior unaddressed, which is minor for a single-entity getter.

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 baseline is 3 and the schema already documents both parameters and the enum. The description still adds value by linking 'id' to its provenance ('Marker-id aus bk_search_blutwerte') and confirming names are accepted, which helps an agent construct the call without a prior lookup.

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 ('Liefert einen Marker der Blutwerte-Seite vollständig') and enumerates exactly what comes back: Bedeutung, Referenzbereich, Zielbereich, hohe/niedrige Werte, Hebel, Störfaktoren, Podcastfolge. This distinguishes it from the sibling search tool bk_search_blutwerte without the agent needing to open a schema.

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 a concrete usage pattern ('Typische Frage: Mein ApoB ist 110 - was heißt das? -> id=apob, dann gegen referenz und optimal einordnen') and implies the id originates from bk_search_blutwerte. It never states when NOT to use this tool or names a competing sibling explicitly, so it falls short of a full when/when-not/alternatives statement.

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