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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real value beyond them: the upstream source (Kadaster BAG via PDOK), the exact price (0.002 USDC via x402 or 1 API credit), and the free-tier rule (first 5 paid-tool calls per day, no payment or key required). Pricing and auth expectations are exactly the kind of behavioral context annotations cannot express.

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?

Front-loaded with the trigger condition and the return payload before pricing details, and every sentence carries distinct information. Slightly dense at four clauses in one paragraph, but no filler.

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, yet the description enumerates the return fields (latitude/longitude, BAG ids, municipality, province, CBS neighbourhood code), and it covers cost, auth path and free tier. Nothing material for calling this paid geocoding 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; the description earns an extra point by explaining the two mutually exclusive input modes ('postcode + house number or free text'), which is a semantic constraint the schema itself does not state since no fields are marked required or exclusive.

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 ('check that a Dutch address exists or get its exact spelling and coordinates') and enumerates the returned BAG fields, so the operation is unmistakable. It does not, however, name or contrast itself with close siblings such as nl_address_reverse, nl_postcode_addresses or nl_address_batch, so an agent must infer the boundary.

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 opening clause gives an explicit trigger condition ('Use when you need to check that a Dutch address exists or get its exact spelling and coordinates') and the third sentence lists concrete scenarios (onboarding, delivery, CRM). No when-not-to-use or named alternative is given, which keeps it 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.