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

Annotations already establish readOnly, non-destructive, closed-world behavior, and the description adds substantive context on top: results retain the journeys graph (steps, edges, prefixes when start or end is set), carry truncation metadata and warnings, and 'counts are journeys' rather than users. That last point is a genuine semantic disclosure an agent would otherwise get wrong; only rate limits/performance characteristics are absent.

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 purpose is front-loaded and every sentence carries information, but the closing sentence is a semicolon-chained run-on that packs defaults, optionality and the guide prerequisite into one dense blob. Splitting that tail would improve scannability without losing content.

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 nested, 6-parameter analysis tool with an output schema and annotations, the description covers what the tool computes, what the result retains, truncation/warning behavior, and the prerequisite guide. The main residual gap is the meaning of the core definition knobs (kind, mode, gap_seconds, window_seconds), which are delegated entirely to the referenced guide topic.

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 coverage is 83%, which alone would justify a 3, but the description adds meaning the schema does not: filters, cleaning_rules and excluded_items default to empty (clarifying the null-vs-empty semantics of those nullable arrays), while start, end and breakdown are optional and the remaining definition fields are required. It still says nothing about mode, kind, gap_seconds, window_seconds or max_steps, which are the semantically hardest fields.

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 opening clause names a concrete verb and resource: 'see the journeys users or sessions take through events', with a worked example (page_view labelled by page) and the start/end/breakdown shaping. It is clearly a path-analysis tool, distinguishable in practice from d8a_run_funnel, though it never names that sibling to sharpen the distinction.

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?

Gives real usage context: read d8a_get_tracking_guide topic journeys-definition first, and 'No compare: run it twice with different dates' tells the agent how to accomplish comparison. It stops short of explicitly contrasting with d8a_run_funnel or d8a_run_query, so alternative selection is left partly to inference.

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