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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds that grouping sends groupBy=customerId-ish behavior and that the range is optional-filterable, but says nothing about pagination, result volume, or the shape of 'total usage', which matters for a 5-parameter aggregation call.

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?

Two compact sentences with the scope stated before the optional modifiers, no filler. The trailing 'API: GET /usage/all' is marginally useful for an agent that already has the tool schema, keeping it just short of a 5.

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?

With no output schema, the description must carry the burden of explaining what comes back, and 'total usage' is left vague (per-bucket totals? summed? units?). The 100% schema coverage and readOnly annotation cover inputs and safety, so the gap is narrow but real for an aggregation tool.

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 five parameters, including defaults and the enum for time_grouping_interval, are already documented. The description restates the customer grouping/filtering semantics in prose but adds no syntax, default, or unit detail beyond the schema, making the baseline 3 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?

States a specific verb and resource ('Get total usage across all meters') plus the scoping dimension (time range, grouped or filtered by customer), which distinguishes it from the single-meter amberflo_get_usage sibling. It never names that sibling explicitly, so an agent must infer the division of labor.

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?

Usage is implied rather than stated: 'across all meters' suggests this is the aggregate alternative to amberflo_get_usage, and the optional grouping/filtering hints at when to use it. There is no explicit when-to-use/when-not statement, no mention of the sibling by name, and no prerequisites.

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