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

Annotations already convey readOnly, idempotent, and non-destructive behavior. The description adds some return-shape context ('compact totals and daily costs') and normalization, but doesn't disclose aggregation details, date handling, or error behavior. No contradiction with annotations.

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 two short sentences with no filler. The main action and return type are front-loaded, making it highly scannable.

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 6 optional parameters, 0% schema description coverage, and no output schema, the description is too thin to fully support correct invocation. It omits parameter semantics, default behaviors, and output details, leaving significant gaps.

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 0%, and the description only hints at 'date range' (covering start_date/end_date/days_back). Parameters like account, group_by, and bucket_width are completely unexplained, leaving the agent without enough information to set them correctly.

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 uses a specific verb ('Get') and resource ('normalized Anthropic cost report') with date-range scope. It clearly states what the tool does, but doesn't explicitly distinguish it from the sibling tool anthropic_billing_usage, so it misses 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?

The description implies when to use the tool—when a normalized cost report over a date range is needed—but provides no explicit exclusions or alternatives. It doesn't mention why to choose this over anthropic_billing_usage or list_accounts.

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