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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral context beyond that: the 25-boat result cap, the 'exact total_matches after price and date filtering', the normalization of English/German/French terms, and date semantics excluding 'booked'/'blocked' boats. This is exactly the behavioral information an agent needs that the schema cannot convey.

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 tightly packed sentences: purpose, filter enumeration, return behavior. The purpose is front-loaded, nothing is repeated from the schema verbatim, and every sentence earns its place. Highly efficient.

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 search tool with 8 optional parameters and no output schema, the description covers all filter categories, the return shape, the result cap, and normalization behavior — strong coverage. Minor omissions such as sort order and explicit sibling routing keep it just short of fully complete.

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 75% (limit and min_capacity lack descriptions), so the baseline is 3. The description adds some value by specifying the YYYY-MM-DD date format and the normalization behavior for type and country names, but it only summarizes the filter categories at a high level and does not fill the gap for the two undocumented parameters.

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 — 'Search Obato's rental fleet (verhuur)' — with a scope that is clearly distinct from siblings like search_boats, since this is specifically about rental inventory. However, it never explicitly names the sibling it is not (e.g., 'for the full fleet use search_boats'), so differentiation is implicit rather than stated.

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 'rental fleet (verhuur)' framing and the date-based availability filter imply the intended use case: finding boats available to rent on a given date. But the description gives no explicit when-to-use versus when-not-to-use guidance and names no alternatives among the ten siblings, so an agent must infer the boundary with search_boats.

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