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

Annotations already cover safety (readOnly, idempotent, non-destructive), yet the description adds material facts they cannot: the upstream source (Rijkswaterstaat LIWO, AHN), the exact price (0.004 USDC via x402 or 2 credits), and the five-free-calls-per-day waiver. Payment requirements and data provenance are exactly the behavioral context an agent needs before calling a paid tool.

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?

Three sentences, front-loaded with the trigger condition, then data coverage, then input and cost. Every clause carries information, though the middle sentence is a dense run-on list that could be tightened.

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?

There is no output schema, so the description must describe returns — and it does, naming every returned metric and its climate scenarios. Combined with input shape, data source and pricing, an agent has everything needed to invoke this correctly.

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. The description goes further by stating 'Input: postcode + house number', which resolves genuine ambiguity — the schema declares zero required parameters and never says which of the five fields form the canonical combination (and that q is an alternative). It still doesn't mention the free-text q path, keeping it below 5.

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 and resource ('asks if a Dutch address can flood') and enumerates the exact outputs: annual probability at 20/50/200 cm, 2050/2100 scenarios, worst-case depth, ground height. The Dutch-address + flood-risk scope cleanly separates it from siblings like nl_house_prices or nl_home_report.

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?

'Use when the user asks if a Dutch address can flood' gives a crisp activation condition, and the cost/free-tier note helps the agent decide whether to invoke it now. It does not name a sibling alternative or state when NOT to use it, so it stops short of a 5.

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