gx3_xref_where_used

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

With no annotations, the description must disclose behavior on its own. It reveals a prerequisite (xref DB) and an output convention (repeat the device comment instead of reporting a bare device number). It does not mention whether the tool is read-only, how errors are handled, or the full output shape, but the provided traits are useful and non-obvious.

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?

The description is two sentences, front-loads the core purpose, and packs the prerequisite and output instruction without waste. Every clause earns its place.

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 simple two-parameter lookup tool with no output schema and no annotations, the description covers the essential operational context: what it returns conceptually, how to prepare the environment, and how to format the answer. It omits a fuller return format description, but that is not critical given the simple use case.

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 description coverage is 100%, so the schema already documents both root and device. The description adds a minor nuance by tying root to the xref build command, but it does not define what 'POU name and real step' means for the device parameter. This meets but does not exceed the baseline for full schema coverage.

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 the tool identifies 'writers and readers of a device', which is a specific resource and lookup operation. The 'with POU name and real step' qualification adds scope, and the name 'where_used' reinforces the cross-reference purpose. However, it does not explicitly use a verb like 'list' or 'find', and the phrasing is somewhat jargon-heavy.

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 a clear prerequisite: the xref DB must be built once per project, with an exact command. It does not, however, distinguish when to use this tool versus siblings like gx3_trace_device or gx3_data_flow, nor does it mention when not to use it.

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