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

With readOnlyHint=true and openWorldHint=false already declaring safety, the description adds real behavioral detail: the compare mode joins groups with previous values and deltas, time series return as two separate series, and deltas are observational rather than causal. That is meaningful context an agent would otherwise have to infer.

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?

Front-loaded with 'Use this to...' and the candidate question types, then semantics, then sibling routing at the end. Dense but each sentence carries information; the causality caution and label-presentation note are the only lines that could arguably be trimmed given the output schema exists.

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?

Output schema exists so return values need not be described, yet the description still covers the tricky compare-mode result shape. For an 11-parameter read tool it covers what is needed to call it correctly; only filtering/ordering behavior beyond the schema is left implicit.

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 100%, so baseline is 3, and the description goes beyond it: columns use exact catalog IDs and can carry a time_bucket transformation, dates are inclusive YYYY-MM-DD in the property timezone or a preset. This gives practical invocation meaning the schema's field descriptions alone only partially convey.

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 sentence names a specific verb (answer questions with numbers) plus the concrete output shapes: dimension tables, time series with a time_bucket column, goal conversions, and period comparisons. It explicitly distinguishes itself from d8a_run_funnel and d8a_run_paths, so an agent can route without opening the schema.

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?

Explicitly says to use d8a_run_funnel for funnels and d8a_run_paths for journeys instead, giving the agent clear positive routing. It never states when not to use this tool for other cases (e.g. saved reports, catalog lookup), so it falls short of full when/when-not coverage.

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