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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive. The description adds substantive behavioral context beyond those annotations: real-time flagging on official data prints, partial degradation behavior, Ed25519-signed outputs, and a first-3-calls-free access rule. These details help an agent understand runtime expectations and constraints.

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 compact and front-loaded with the core definition before caveats. Each clause earns its place, though 'Partial degradation' is a bit vague and the free-tier note is more commercial than functional. Overall it is efficiently structured.

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 description gives enough to understand the tool's purpose and selection, and an output schema exists to cover return values. But the optional parameter's expected format is unclear, and 'Partial degradation' is never explained. This is adequate but not 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 description coverage is 100% for the single optional input string, which sets a baseline of 3. However, the schema's Spanish description 'parametros del producto (JSON o texto)' is generic and does not explain what JSON or text this macro-surprise tool expects. The tool description itself adds no parameter-specific meaning.

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 states a specific quantitative concept (z-score of the latest change vs the trailing 12-change distribution), names the exact official ECB series covered, and explicitly says the tool 'flags strong/moderate surprises' on data prints. This is specific enough to distinguish it from broad siblings like market_sentiment or macrobundle.

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 phrase 'Flags strong/moderate surprises the moment official data prints' implies a clear trigger for use, but the description does not explicitly mention when to avoid this tool or name alternatives among the many siblings. Usage context is implied rather than stated.

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