list_kb_products

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

Annotations provide readOnlyHint=true and openWorldHint=true, and the description reinforces these with 'Read-only; no side effects'. Beyond the annotations, the description discloses critical behavioral traits: the non-obvious default (no argument returns only PI System products, not everything), the caching behavior for process lifetime, the return format (one name per line, alphabetical), and the 'note if nothing matched' outcome. The scale context ('over a thousand product names') explains why this default exists. All of this is additive value that annotations cannot express.

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 sentences in a purposeful order: purpose, usage guidance with concrete examples, behavioral caveats, return format. Every sentence carries distinct information with zero filler. The slight redundancy of 'Read-only; no side effects' against the annotation is acceptable reinforcement rather than waste. Front-loaded with the core purpose, which is exactly what an agent scanning tool lists 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?

For a tool with one optional parameter, an output schema, and strong annotations, the description is complete. The most dangerous gotcha — that omitting the argument does not mean 'all products' but rather 'PI System products only' — is explicitly highlighted. The description covers when to use, when not to use, default behavior, caching, output format, and empty-result behavior. Nothing an agent would need to call this 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 coverage is 100% and the schema description is already strong with worked examples ('vision', 'historian', 'adapter'). The description adds one useful clarification beyond the schema: passing `contains` expands beyond the default PI System set ('find products outside that set'), which resolves an ambiguity in the schema's phrasing 'Omit to list PI System products only' — one might otherwise infer contains merely filters within that set. That semantic disambiguation is real value, though the schema does most of 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 first sentence states a specific verb ('List'), a specific resource ('AVEVA product names'), and ties it precisely to the products argument of the sibling tool search_pi_kb. It is immediately distinguishable from both siblings: search_pi_kb (which searches articles) and get_kb_article (which retrieves a single article). This is textbook purpose clarity.

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 gives two explicit trigger scenarios (narrowing cross-product search results by exact spelling, and resolving informal user names like 'PI AF' to AVEVA canonical form) and an explicit exclusion ('Not needed for a first, unscoped search'). It also names the sibling tool whose results this tool supports, giving the agent a clear decision rule for when to call it.

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