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

Annotations already declare readOnlyHint=true. The description adds valuable behavioral context beyond that: it explains the z-scored composite, the underlying ETFs (KRBN, KCCA, KEUA), the trailing one-year window, daily refresh, and output fields like symbols_failed. This goes beyond the annotation's bare read-only signal.

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 information-dense. Each sentence serves a clear purpose: what it returns, when to use it, and update frequency. No filler or redundant phrasing.

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 single optional parameter, read-only tool with no output schema, the description and schema together provide all necessary context: return fields, refresh cadence, use cases, and parameter behavior. Nothing critical is missing.

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 coverage is 100%, and the 'days' parameter is well-documented in the schema (including the Gold tier requirement and fallback behavior). The description does not add extra meaning about parameters, which is acceptable given the schema's thoroughness; baseline 3 applies.

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 verb ('Returns') and a precise resource ('0-100 carbon credit liquidity score') with detailed methodology and output fields. It clearly distinguishes this tool from siblings by spelling out its unique role in carbon market liquidity.

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 explicit when-to-use guidance: 'Call when the user asks about carbon market liquidity, allowance ETF tradability, or EUA/CCA market depth, or when timing compliance purchases, carbon position entries or exits, or order sizing.' It lacks explicit when-not-to-use or sibling alternatives, so it falls short of a 5.

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