root_cause

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

No annotations are provided, so the description carries the full burden. It discloses the walk order, the logic (first unhealthy layer), and the reporting behavior. It does not mention side effects (likely read-only) or error cases, but for a trace tool this is a reasonable level of transparency.

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?

Three sentences, each serving a purpose: purpose, algorithm/reasoning, and input constraint. Front-loaded with the primary action, no unnecessary fluff.

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?

Covers purpose, algorithm, and input constraint, but does not specify the exact return format (e.g., whether it returns the layer name, a report object) or the behavior when all layers are healthy. Given there is no output schema, this is a minor gap for an agent invoking the 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 description coverage is 0%, so the description must compensate. It does so by adding a crucial constraint: 'site must exactly match a name returned by list_sites.' This gives meaning to the single parameter beyond the bare schema, making the input unambiguous.

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?

States a specific action: 'Trace the most likely root-cause layer for a site's issues.' Describes the algorithm (walks circuit, power, core, access in dependency order) and the output (first unhealthy layer). This clearly differentiates it from siblings like site_health or degraded_sites, which focus on status or listing rather than root-cause analysis.

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?

Provides context for when it is appropriate ('an upstream issue typically explains downstream symptoms') and a prerequisite ('site must exactly match a name returned by list_sites'). However, it does not explicitly mention alternative tools or when NOT to use this one, leaving some ambiguity for the agent.

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