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

Annotations already provide readOnlyHint=true and openWorldHint=false. The description adds valuable context: update frequency ('Updates: daily'), data source (EUR-Lex/CELLAR), and score construction details, which go beyond the 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?

Two sentences pack purpose, methodology, output fields, use cases, and update frequency without redundancy. Information is front-loaded and every clause 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?

No output schema exists, but the description enumerates return fields (trend, z_score, recent_window_count, baseline_window_mean, per_variant_w0) and defines the score. It covers what the tool returns and when to use it. Minor gap: does not elaborate on per_variant_w0 breakdown, but the optional history parameter is covered by the schema.

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 fully explains the sole 'days' parameter, including the Gold tier requirement and fallback behavior. The tool description adds no additional parameter semantics, so the baseline 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 uses a specific verb 'Returns' and clearly defines the metric as a '0-100 EU legislative output velocity score' with data source and scope. It distinguishes itself from sibling tools by naming the exact topic and methodology.

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 states when to call: 'when the user asks about EU regulatory activity, rule-making pace, or compliance-burden build-up' and 'when timing EU compliance staffing, budget, or market-entry decisions.' Does not mention alternatives or exclusions, which prevents a 5.

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