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

The annotations already declare readOnlyHint=true, so the agent knows this tool is safe to call, and the description adds genuinely useful behavioral context: the source is the NDW and the data refreshes every five minutes. It does not say whether results are capped, how large the response can get, or what happens when a road or place is unknown, and because there is no output schema, those gaps matter more.

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 description is two compact sentences that front-load the core resource and the refresh cadence, then add the filtering options. Nothing is wasted, although the field list and the filter clause in the second sentence make the description slightly dense.

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?

For a two-optional-parameter, no-output-schema tool, the description covers the source, freshness, returned fields, and filter behavior, which is nearly everything an agent needs. It leaves open whether 'weg' and 'plaats' can be combined and whether an unfiltered call returns all jams nationwide, but these are minor gaps.

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%, and the schema already documents both optional parameters, including the 15 km radius around a place. The description only adds concrete example values (A28, N34) and confirms that a filter is optional when neither is supplied, so the baseline score of 3 is appropriate.

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 description gives a specific verb-plus-resource: the traffic jams currently on Dutch roads, from the NDW feed, with the fields returned (road, section, length, delay). It is clear what the tool does, but it never differentiates itself from the sibling tool 'verkeer', which an agent could easily mistake for the same data.

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 only usage guidance is about the optional filters ('optioneel voor één weg of rond een plaats'), which is parameter guidance rather than when-to-use-this-tool guidance. There is no indication of when to prefer this over the sibling 'verkeer' tool, and no exclusion or alternative is named.

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