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

Annotations already cover safety and idempotency, and the description adds genuinely new behavioral context: the values are manufacturer statements, not Synergrid approval, and each value carries a status (verified vs. secondary) plus provenance (source URL and page, date last verified). That caveat is exactly the kind of trust/interpretation guidance annotations cannot convey; only the output format is left implicit, which the output schema covers.

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?

Purpose and the critical approval caveat are front-loaded, which is good, but the long middle enumeration of return fields is partly redundant with the existing output schema and dilutes the two sentences that actually matter. It reads as a single dense block rather than a structured note.

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 lookup with an output schema and full schema coverage, the description supplies the missing interpretation layer: data provenance, verification status, and the boundary against the approval tool. What remains unstated — behavior with no lookup key given the zero required parameters — is minor.

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 brand, model, reference and locale are all documented in the schema, including the "alternative to brand and model" relationship. The description's lookup sentence largely restates that, and it adds nothing about locale behavior or what happens when neither lookup mode is supplied (zero required 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?

The description opens with a specific verb and resource ("Returns manufacturer datasheet data for an inverter") and names the exact source (Synergrid C10/26 list), then enumerates the concrete fields returned. An agent can distinguish this immediately from the approval-checking sibling.

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?

It explicitly routes approval questions to check_inverter_c10_26 and states the two lookup modes (Synergrid reference vs. brand+model). It does not mention the other inverter sibling suggest_inverter_c10_26, so the routing picture is clear but not exhaustive.

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