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

Annotations already declare readOnlyHint and idempotentHint, and the description adds valuable methodological context: BLS publishes index levels, not rates; the tool computes YoY from NSA data and MoM from SA data. This explains behavior beyond the structured annotations without contradiction.

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 well-organized with clear sections ('When to use', 'When NOT to use', 'Args', 'Returns structuredContent'). Every sentence adds value, and the sample output makes the structure concrete without bloat.

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?

Despite lacking an output schema, the description provides a full structuredContent example with field names and sample values, covering asOf, periodName, headline, and core. It explains the data source and the computation method, making it complete for a simple read-only 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?

The tool has zero parameters, so the description appropriately states 'Args: none.' With no parameters to document, the baseline of 4 is met. The description could have added even more context about parameterlessness, but it's already explicit.

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 verb and resource: 'Latest U.S. CPI inflation from the Bureau of Labor Statistics, with the rates already computed.' It specifies exact outputs (headline and core CPI, YoY and MoM) and naturally distinguishes from siblings like macro_pce by mentioning what it does not cover.

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?

Explicitly includes 'When to use' (need current inflation rate, real-vs-nominal adjustment, CPI context) and 'When NOT to use' (PCE, regional/category-level detail, long historical series). Names the alternative (PCE) and clarifies the tool's scope relative to siblings.

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