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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the description earns credit for adding scope and mechanics: fuel-card data is explicitly excluded from results, and it discloses keyset pagination ('Returns one page... pass next_cursor as start_cursor'). It stops short of auth, rate-limit, or result-size details, but the pagination and data-exclusion notes are real additions.

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?

Four short sentences, front-loaded with the resource and payload, then filters, then the data-exclusion caveat and pagination rule. The raw 'GET /fuel_entries' line is marginal filler for an agent but is small; otherwise there is no wasted text.

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 read-only, 12-parameter list tool with no output schema, the description must carry return-shape and paging information, and it does: it enumerates returned fields and explains the one-page-plus-cursor loop. It does not cover default page size or empty-result behavior, but nothing essential to calling it correctly is missing.

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 all 12 parameters (sort_by, per_page, vendor_id, date/created_at/updated_at bounds, cursors) are already documented by the schema. The description's filter summary restates what the schema provides and adds no new param semantics, so the baseline 3 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 verb and resource ('List fuel purchases/fill-ups') and immediately enumerates the returned fields (vehicle, volume, price, total cost, efficiency), which distinguishes it from the many sibling list tools such as fleetio_list_meter_entries or fleetio_list_service_entries. An agent can identify this tool without opening the 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?

The description names the filter dimensions ('Filter by vehicle, vendor or date'), which implies when the tool is useful, but it never states when to prefer another tool or any prerequisite. Usage is inferable but not explicit, which is the definition of a minimum-viable 3.

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