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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the description does not need to restate safety. It adds useful behavioral context not in the annotations: output is ordered, limited to nine published areas, includes descriptions and group labels, and locale selection switches between English and Hebrew.

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 with no filler. It front-loads the what, then the why, then the parameter guidance, and every phrase contributes useful information.

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 list tool with one optional enum parameter and an existing output schema, the description is complete. It covers scope, content, ordering, localization behavior, and the primary usage intent, without needing to duplicate output schema details.

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 0%, so the description must carry the semantic weight for the locale parameter. It fully does: it explains that 'he' produces Hebrew titles and descriptions, that the default is 'en', and implicitly that only en and he are supported by the schema enum.

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 uses a specific verb ('list') with a clear resource ('nine published Truss service areas') and states exactly what is returned: an ordered index with short descriptions and human-readable group labels. The phrase 'Prefer this tool for "what does Truss do?"' signals its role as an overview tool and implicitly distinguishes it from the sibling detail tools get_truss_service and get_truss_information.

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, actionable usage cue: use this tool when the user asks what Truss does. It does not explicitly mention when not to use it or name alternatives by tool name, so it stops short of a full when/when-not contrast, which would earn a 5.

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