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

readOnlyHint=true already establishes this is a safe read. The description adds genuine behavioral context the annotation does not: the covered domain (Bulgarian cities only), the metric shape (active listing count, median rent in EUR), and the dependency role (source of city slugs). It does not state freshness or ordering of the data, which is a minor gap.

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 sentences, both earning their place: the first describes content, the second describes the calling workflow. The most actionable instruction (call first) is placed last but is short and easy to retain; nothing is padded or redundant.

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 correctly compensates by describing the return fields and the slug concept, which is what downstream tools consume. For a one-optional-parameter lookup tool this is nearly complete; only data freshness/ordering is left implicit, which is acceptable given the structure.

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% and the single 'language' parameter has a documented enum with a stated default, so the schema fully carries parameter semantics. The description adds nothing about the language option, 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 specific verb ('Lists') and resource ('Bulgarian cities covered by Domly') and goes further to name the return payload: active listing counts and median monthly rent in EUR. An agent can immediately distinguish this from get_listing, get_price_stats, search_listings, and request_realtor.

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 explicit sequencing guidance: 'Call this first to get city slugs for the other tools,' which tells the agent exactly when this tool is appropriate relative to its siblings. It does not name a tool to avoid or a when-not condition, but the entry-point role is unambiguous.

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