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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds real behavioral value beyond that: results are sorted by average monthly price over the contract term, prices are 'actuele' (live), and availability is address-dependent, implying empty results for uncovered addresses.

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?

Two sentences, purpose front-loaded, second sentence covering outputs and the address caveat. Slightly redundant phrasing ('internet en internet met tv') costs a little, but the text is well-sized and free of 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?

With no output schema, the description correctly compensates by enumerating returned fields (snelheid, actieprijs, normale prijs, looptijd, link) and the sort order, plus the availability caveat. Only minor gaps remain, such as default result count/limit behavior and what an empty result set means.

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 the schema already explains all six parameters and the agent needs no help from prose. The description echoes provider and connection values (KPN/Odido/Youfone, glasvezel/kabel/dsl) but those are already enumerated in the schema, so it adds little beyond the baseline.

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 names a specific verb (Zoekt), the resource (internet en internet met tv voor thuis), the geography (Nederland), the providers (KPN, Odido, Youfone) and connection types (glasvezel, kabel, dsl). It also states the sort order (gemiddelde maandprijs over de looptijd), which cleanly separates it from the phone/sim/device siblings.

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?

Usage context is only implied: an agent can infer this is the tool for home internet/tv deals, and the note that availability depends on the address hints at a precondition. However, no alternatives are named and there is no explicit when-to-use/when-not statement, so the routing guidance stops at inference.

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