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

Annotations already declare readOnlyHint=true, so the description doesn't need to restate that. It adds value by disclosing that the output includes ordered steps, per-node events, and stop/why information—behavioral details not inferable from annotations. 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?

Two concise sentences with zero filler. The first sentence states the core function, the second explains the primary use case. Information is front-loaded and every phrase 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 read-only, single-parameter tool, the description is complete: it explains what the output contains (ordered steps, node events, stop reason) and why it's used. It doesn't cover error handling or output format, but the simplicity and annotations make that acceptable.

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?

The schema covers the only parameter, run_id, with a minimal description ('The journey run id'). The tool description doesn't add any further meaning about run_id. Since schema coverage is 100%, the baseline of 3 applies; the description adds no extra parameter semantics.

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 a specific verb and resource: 'List the steps of a journey run in order, with each node and what happened at it.' This clearly distinguishes it from sibling tools like get_journey_run (which retrieves run-level info) and list_journey_runs (which lists runs, not steps). It also adds specific output details that set it apart.

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 use case: 'This is how to see where a run stopped and why.' This tells an agent when to use the tool, but it doesn't explicitly mention alternatives or when not to use it. However, the context is sufficient for most selection scenarios.

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