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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely non-structured context: the tool is free, it aggregates from three named public sources, and it returns comparative figures (crime vs national rate, liveability percentile) rather than raw data. It does not discuss latency, coverage gaps, or what happens for an unknown postcode, which keeps it below 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?

Front-loaded with the two pieces an agent needs first ('Free. Use when...') followed by one dense but well-ordered sentence listing the payload fields and sources. No filler sentences, though the enumerated output list runs long and 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 carry the return-value burden, and it does: it enumerates each headline metric and names the upstream sources. Combined with annotations covering read semantics, an agent has everything needed to call this correctly and describe the result to a user.

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%, so both parameters (postcode and optional CBS buurt code) are already documented with examples in the schema. The description only implies postcode-based input ('headline facts for a postcode') and adds nothing about the alternate code parameter, so the baseline 3 for high-coverage schemas 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 resource (Dutch neighbourhood/postcode summary) and enumerates the exact headline facts returned: residents, WOZ home value, owner-occupied share, liveability percentile, crime per 1,000 vs national, and distances to amenities. The 'Free' marker and explicit data sources (CBS, Politie, Leefbaarometer) let an agent place it against siblings like nl_home_report and nl_crime without opening any schema.

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 a clear triggering condition: 'Use when the user asks what a Dutch neighbourhood or postcode area is like, or whether it is safe.' That is a strong when-to-use signal, but it names no alternative tool for adjacent needs (e.g. street-level lookups via nl_address_lookup or a single-topic nl_crime query), so the routing 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.