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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral value beyond that: it enumerates the returned content (likely causes, safe checks, safety warnings) and states a hard scope limitation ('Never returns part numbers'), which sets expectations about what the agent will not get back.

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, input guidance front-loaded after the purpose, and the output/limitation statement placed last. Efficient overall, though the opening 'Honest troubleshooting from working appliance technicians, grounded in real completed repairs' leans promotional rather than informative.

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 usefully explains what comes back (causes, safe checks, warnings) so the agent knows the shape of the response. Remaining gaps are minor — no guidance on result trust level or follow-up actions — for a read-only diagnostic tool.

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 80% and the schema already carries descriptions for model, symptom, appliance, and error_code. The description names the same five inputs and marks brand/model/error_code as optional ('if known'), but adds no formatting, syntax, or example detail beyond what the schema provides — baseline 3 when the schema does the heavy lifting.

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 states a specific verb and resource — troubleshoot/diagnose an appliance problem from real repair data — and is obviously distinct from booking or business-info siblings by nature, though it never names an alternative tool explicitly. An agent can tell what this tool is for 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?

It tells the caller what to supply ('Give the appliance and symptom, plus brand, model and any error code if known'), which is useful invocation context, but gives no when-to-use vs when-not guidance relative to siblings like book_repair (e.g., diagnose first, book only if a repair is needed). Usage is implied rather than routed.

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