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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false. The description adds useful non-schema context: the series is monthly, the data source is ECB SDW, and no authentication is required. This complements the annotations without repeating them.

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?

Three compact sentences: definition, series frequency + filtering, and data source/auth. Zero fluff, information is front-loaded with the core purpose first. Every sentence 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 simple read-only tool with 3 optional params and an output schema, the description covers the essential context: what the series is, its frequency, filtering options, data source, and auth requirements. It doesn't explain return values, but the output schema already does. Minor gap: no mention of data availability or historical depth, but not critical.

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%, and the schema already documents each parameter's format, precedence, and defaults. The description only restates 'Filter by last_n_observations or start_period/end_period', which adds no new semantic meaning beyond the schema. Baseline of 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 names a specific verb ('Get'), a specific resource ('euro area HICP all-items annual rate of change'), and adds context ('ECB's official inflation measure used for its 2% target'). This clearly differentiates it from siblings like bls.macro.cpi or finance.eurostat.inflation, which cover other regions or measures.

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 gives clear context for when to use this tool (euro area inflation, ECB target measure) and explains the filtering options. It does not explicitly name alternatives or when not to use it, but the 'euro area' qualifier and 'ECB's official measure' phrasing provide strong situational cues without needing exclusions.

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