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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: it returns a group_note for groups >5, explains that Kärnten Card does NOT cover Römerbad Thermal Spa, and notes the HPP partnership for Greenfee. It does not describe pagination or exact response structure, but for a read-only availability check the added context is solid.

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 description is well-structured with a clear opening, a return summary, a routing note, and a parameter list. It is longer than average, but every sentence earns its place by adding operational detail. The only minor issue is that the Kärnten Card / Greenfee / Römerbad notes, while useful context, are somewhat tangential to the core call and could be trimmed or moved to a notes section.

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?

For a read-only availability tool with no output schema, the description is complete: it states what is returned, how to handle groups, how to pass children, and how to choose language. It also names the sibling render_availability_card for the visual follow-up. An agent has everything needed to call this tool correctly and interpret the result.

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 0%, so the description carries the full burden for parameter semantics. It does this thoroughly: check_in/check_out get format examples, adults gets a detailed explanation of total vs per-apartment semantics with group-size examples, children gets age semantics ('under 17') and format guidance, and language gets a clear default and a rule for when to use 'en'. This far exceeds what the schema provides.

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?

The description states a specific verb ('Check real-time availability'), a specific resource ('holiday apartments at Landhaus Prägant, Bad Kleinkirchheim, Austria'), and the return content (apartments with nightly rates, cleaning fees, tourist tax, total price). It also explicitly distinguishes itself from render_availability_card, so an agent can tell it apart from siblings without opening schemas.

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 gives explicit when-to-use guidance: it is the data-only version, and the agent should call render_availability_card with the same arguments after reviewing this result. It also provides parameter-level usage rules (e.g., adults is the total group size, not per-apartment limit; language should match the conversation language). This is strong routing and usage context.

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