Get postcode

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds value by naming the return fields and the downstream id handoff, but says nothing about lookup-miss behavior or the fact that both parameters are optional (required: 0), leaving the 'neither supplied' case undefined.

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 compact sentences, front-loaded with the core action and return shape, followed by a concrete example and a workflow handoff. The example earns its place; nothing is padded, though the second sentence carries two distinct ideas.

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 only two params, no output schema and no nested objects, the definition is nearly self-contained: it names the return fields and the follow-up tool. The remaining gap is the optional-parameter edge case, which neither the description nor the schema resolves.

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 baseline is 3, but the description adds real semantics beyond the schema: it frames the two parameters as alternative lookup keys ('by its 4-digit code or by UUID'), which the schema does not state, and ties the returned id to the postcode_id parameter of another tool.

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 (Fetch) and resource (Danish postcode/postnummer) with the two accepted key forms, and enumerates the returned fields (id, code, name, status). This clearly separates it from sibling getters like dar_get_street, dar_get_address and dar_get_access_address, which target different entities.

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?

Provides a concrete example call and, more importantly, states the downstream usage: pass the returned id as postcode_id to dar_list_access_addresses. That routes the agent through a real workflow. It stops short of explicit when-not guidance or stating what happens if neither identifier is supplied.

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