jd_get_machine_engine_hours

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds value beyond that by disclosing the cross-tool dependency on jd_list_equipment for principal_id and by stating which key the readings are returned under, letting the agent plan a two-call flow.

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, zero filler, and front-loaded: purpose first, then return shape, then parameter source, then mode selection. Each sentence carries distinct information an agent needs.

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 an output schema present and full schema description coverage, the description needs only to add dependencies and mode semantics, which it does. It is nearly complete; pagination or result-size limits for a date-range history query are the only unaddressed concern.

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 further by explaining how last_known relates to the start_date/end_date window (mutually exclusive modes) — semantics the schema presents only as three independent optional fields. It adds real meaning on top of the schema.

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 ('Get engine hour readings for one machine') and names the returned payload key, so the agent knows exactly what comes back. It does not explicitly differentiate itself from the adjacent sibling jd_get_machine_hours_of_operation, which is the one name an agent could plausibly confuse it with.

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 usable mode-selection guidance: last_known=True for the current total versus a start_date/end_date window for history, plus the provenance of principal_id. It stops short of any when-not-to-use or explicit sibling routing, which is the only gap.

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