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 value beyond that by disclosing the return contents (including open viewings with ids) and the accepted id forms, which is real behavioral context. 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?

A single front-loaded sentence opens with the purpose before the parenthetical detail. It is dense but every clause carries information (id sources, return payload, preconditions). Slightly heavy for one sentence, keeping it below a 5.

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 no output schema, the description compensates by enumerating exactly what the agent gets back, plus valid id inputs, plus when to invoke it. Nothing needed to select and call this read-only tool correctly 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 coverage is 100%, so the baseline is 3, but the description genuinely enriches the `id` parameter by naming its three sources (search_listings output, a Heimster link, or «found:<id>» for agency-website listings) — meaning the bare 'Listing id (UUID)' schema does not convey. The `language` param is left to the schema.

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 uses a specific verb ('show one listing in full') and explicitly enumerates the payload — photos, floor plans, description, costs, location facts, open viewings with ids, and the link. This clearly distinguishes it from search_listings (which finds listings) and from the booking/application siblings.

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?

It gives concrete usage context: 'Call it before booking a viewing or applying,' tying the tool to a workflow step. It also tells the agent where the id may come from. It stops short of naming explicit alternatives or when-not-to-use conditions, so it lands at clear-context-but-no-exclusions.

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