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

With no annotations, the description carries the full burden, and it does add real behavioral context: it reads pre-aggregated calendar-month snapshots ('clean and quick') and discloses the response shape. It does not address permissions or limits, but for a read-only analytical tool the provenance and performance notes are meaningful disclosure.

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 core purpose is front-loaded in the first sentence and each subsequent sentence adds distinct value (use cases, return fields, chart handoff, data source, rendering default). It is dense and slightly long, but no sentence is pure filler.

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?

There is no output schema, so the description must explain returns, and it does so well (rows, charts, totals, seeAlso). Combined with clear usage guidance and full schema coverage, an agent has enough to call it correctly, though a note on pagination beyond the schema's _offset would round it out.

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 100%, so all six parameters are already documented in the schema. The description adds no syntax or format detail beyond that (metric snapshot requirement, year defaults, and store/source filters are all in the schema), so the baseline of 3 applies.

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 names a specific verb and resource ('Month-by-month year-over-year comparison for a single metric') and scopes it to one metric, which implicitly separates it from multi-metric siblings like get_metrics_multi_compare. However, it never explicitly names a sibling or states when to prefer this over get_weekly_trends or get_metrics_comparison, so it falls short of full sibling differentiation.

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?

Strong when-to-use guidance is given via concrete question phrasings ('how is revenue this year vs last year by month?') and an explicit default action ('DEFAULT TO RENDERING THE CHART'). It lacks any when-not guidance or named alternatives, so it stops short of a 5.

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