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

Annotations already cover readOnly/destructive/openWorld, so the bar is low, but the description still adds useful behavior: every row carries 'unit_kind' so mixed vehicle/trailer results stay distinguishable, and it discloses the response envelope {items, total, has_more} including pagination signaling. It does not mention rate limits, max result sizes, or ordering, which keeps it off 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 purpose and defaults, then filtering, then return shape — a well-ordered single paragraph with no filler sentences. The Ukrainian glosses (тягачі / причепи) add length of questionable value to an agent, a minor inefficiency but not noise that obscures meaning.

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 supplies the return shape and the per-row 'unit_kind' invariant, and it covers the discriminating parameters for a 6-param, all-optional listing tool. Pagination semantics (how to advance with offset, max limit 200) are left to the schema, which is acceptable but not fully airtight.

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 only 17%, so the description must compensate and largely does: it explains 'kind' values plus the 'both' default, enumerates status values, and defines 'q' as plate/brand/model search and 'carrier_id' as a carrier filter. The 'limit'/'offset' pair is only implied via 'has_more', leaving one gap that prevents a 5.

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?

Opens with a specific verb and resource ("List the fleet — tractors and/or trailers") and immediately clarifies the 'kind' discriminator, so an agent can tell this apart from create/update fleet siblings and from list_carriers/list_drivers. Scope (read-only listing over two unit types) is unambiguous.

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 clear operating context: default 'kind' is 'both', and filtering is available by status, carrier, or free-text plate/brand/model, which tells the agent how to narrow results. It stops short of naming an alternative tool or stating when NOT to use it, so it lands at clear-context-without-exclusions.

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