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

Annotations only supply readOnlyHint and openWorldHint; the description adds substantial behavioral context on top: a 10-credit cost, a no-charge path for unsupported input, aggregate-only output that never exposes addresses or owners, the matching methodology (cadastral section + plan, then normalized-address fallback), and the anchoring of the 24-month window to the latest available DVF mutation.

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 structure is front-loaded and scannable (purpose, REQUIRED, OPTIONAL, definition, returns, cost), and nearly every sentence carries load-bearing information. It runs slightly long with the matching-method detail, but that detail is defensible for a statistical tool with methodology caveats.

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 the returned aggregate indicators (flip rate, median gross margin, median margin percentage, median holding period, matching-method counts) and explicitly stating what is never returned. Combined with cost and the apartment edge case, an agent has everything needed to call and interpret this tool.

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 adds genuine meaning beyond the schema: the rationale for why apartments are unavailable ('DVF parcel/address matching can't tell flats in the same building apart') and confirmation that code_commune is a compatibility alias rather than a DVF raw commune fragment. It also clarifies the default (Maison) more explicitly than 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 first sentence names a specific verb ('Detects') and a specific, non-obvious resource ('short-hold resales ("flips") in one French commune'), and the body defines exactly what counts as a flip. No sibling tool (search_property_transactions, analyze_price_trends, etc.) covers flip detection, so the agent can route here unambiguously.

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 a partial when-not case by explaining that type_local="Appartement" returns available:false and is not charged, which usefully steers the agent away from a wasted call. However, it never names alternative tools or states when an agent should prefer raw transaction search or market analysis over this aggregate detector, so usage is implied rather than explicit.

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