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

Annotations already mark this as readOnly, idempotent, and non-destructive. The description adds useful context beyond that: it requires a stopped session and reveals whether the agent gets a summary or a per-cluster detail view. It does not describe failure modes for active sessions, but no contradiction exists.

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 tightly structured with a front-loaded purpose sentence followed by concise Parameters and Returns sections. Every element earns its place; the Returns section adds specific value by naming 'severity histogram, bursts, process distribution.'

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?

The description covers the key invocation context: stopped sessions, required and optional parameters, and expected return shapes even without an output schema. It is nearly complete for a simple read-only tool; a small gap is not saying what happens if the session is still active.

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 carries the full burden for parameters. It explains that sessionId is required and that cluster is optional, 1-indexed, and 'drill[s] into one cluster's events.' This adds real meaning beyond the schema, though sessionId format/source is not detailed.

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 names a specific verb and resource: 'Return the full L2 summary for a stopped HangBuster session, or the per-event detail of a specific cluster.' This is clear and specific, but it never explicitly contrasts with siblings like hang-list or hang-stop, so the differentiation is left to the agent rather than stated outright.

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 clear context by saying the target is a 'stopped HangBuster session' and offers a conditional branch for a 'specific cluster.' It does not name alternative tools or exclusions explicitly, but the conditions for using this tool are clear enough for selection.

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