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

Annotations already cover readOnly, idempotent, non-destructive and closed-world. The description adds genuinely new behavior: 'Plain rules, nothing stored' tells the agent the assessment is deterministic and retains no data, and it enumerates exactly what gets flagged (old, high hours, underused, missing info, duplicate IDs) plus a summary. It does not say how results are formatted or ordered, which keeps it short of 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?

One dense sentence with the purpose front-loaded and no filler; the parenthetical input spec earns its space. It is slightly overloaded, packing input format, row limit, and five flag categories into a single clause chain, but nothing is redundant.

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 carries the return-value burden, and it does list the flag categories and the fleet summary. The one gap is the shape of the response (structured report vs. prose), which an agent may need to know before rendering results to a user.

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%, so the baseline is 3, but the description goes well beyond the schema: field order (make, model, year, hours), optional header row, CSV or tab-separated formats, and a 200-row ceiling that the schema's maxLength does not express. This materially reduces malformed-input failures.

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: 'Reviews a pasted fleet list ... and flags old machines, high hours ... with a fleet summary.' The scope (plain rule-based review of pasted text) is unmistakable. It never names a sibling, but the siblings (decode_vin, recall_lookup, equipment_cost_per_hour) are functionally distant enough that confusion is unlikely.

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 is implied rather than stated: the description tells you the tool needs a pasted, line-per-machine list, which effectively defines the trigger condition. There is no explicit 'use when' framing and no mention of alternatives such as decode_vin for identifying a single machine, so the agent must infer routing.

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