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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the scope (whole account, all stores) and the specific metrics included, which is useful context beyond the annotations. However, it doesn't disclose any potential performance implications (e.g., large data volume) or whether the 'days' parameter affects all metrics uniformly. With annotations covering the safety profile, a 3 is appropriate.

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 a single, well-structured sentence that front-loads the core value ('The whole account at a glance') and then lists the specific metrics. The final phrase 'Start here for how am I doing?' is a concise usage hint. No wasted words; every part 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 overview tool with a single optional parameter and no output schema, the description is quite complete. It lists the metrics returned and the scope. The only minor gap is that it doesn't specify the format of the output (e.g., JSON structure), but since there's no output schema, the agent might need to infer that. However, the description's clarity about the content makes this a minor gap. Given the tool's simplicity, a 4 is appropriate.

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% (the 'days' parameter is described as 'traffic window, default 30'). The description doesn't add much beyond the schema, but it does imply the parameter affects the time window for the stats. Since the schema already documents the parameter, the description's minimal addition is acceptable. Baseline 3 is correct when schema does the heavy lifting.

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 clearly states the tool's purpose: providing an account-wide overview of stores with sales, revenue, visits, human/agent split, and buy-intent file views, plus account totals. It uses a specific verb ('get') and resource ('stats'), and the phrase 'Start here for how am I doing?' distinguishes it from sibling tools like get_sales or get_traffic, which likely focus on narrower scopes.

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 explicitly says 'Start here for how am I doing?', which gives clear context for when to use this tool (initial account-level assessment). It doesn't explicitly state when not to use it or name alternatives, but the sibling list and the 'whole account at a glance' phrasing imply that more specific tools like get_sales or get_traffic would be used for narrower queries. This is clear context without explicit exclusions.

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