get_customers_summary

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

Annotations already declare readOnlyHint=true, so the safety profile is known. The description adds the return shape {period, newCustomers} but does not elaborate on aggregation granularity or edge cases. This is acceptable but not rich—hence a 3.

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 sentence with the return signature, tightly packed with no redundant words. It is front-loaded and efficient.

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?

The tool is simple (two dates, a count), and the description covers the return shape. However, the meaning of 'period' is ambiguous—whether it equals the requested range or a breakdown. Without an output schema, slightly more detail would make it fully complete.

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 covers both parameters fully (100% description coverage) with start/end dates and format patterns. The description only confirms 'for a date range,' which adds minimal value beyond the schema. Baseline 3 is appropriate.

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: 'Period-scoped new-customer count for a date range.' This distinguishes it from sibling tools like list_customers (individual details) and get_orders_summary (orders). The return shape {period, newCustomers} further clarifies the function.

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 implies usage context ('for a date range') but does not explicitly state alternatives or when not to use this tool. It provides clear context without exclusions, which aligns with a 4.

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