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

Annotations already indicate readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds beyond this by explaining that data accumulates each time the entity is scored via other ESG tools (esg.lookup, esg.batch, esg.portfolio) – a behavioral detail not captured in annotations. It also clarifies the output includes trend direction and delta. No contradictions with 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?

The description is two sentences with no wasted words. The first sentence states purpose and what is returned. The second sentence adds usage context and a behavioral note. Information is front-loaded and 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?

Given the tool's low complexity (2 parameters, no enums, no nested objects) and the presence of an output schema (so return values are documented externally), the description covers all essential aspects: what the tool does, how data is generated, use cases, and constraints (lookback window). An agent has sufficient context to select and invoke this tool correctly.

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%, with both parameters already well-documented ('20-character GLEIF LEI.' and 'Lookback window in days (7–365). Default 90.'). The description mentions 'by LEI' and 'over the requested window' but does not add meaningful new details beyond the schema. Baseline 3 is appropriate given high schema coverage.

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 opens with a clear verb+resource: 'Get the historical ESG composite trend for a specific entity by LEI.' It then details the returned data (score history, trend direction, delta) and explicitly distinguishes itself from sibling tools (esg.lookup, esg.batch, esg.portfolio) by explaining how data accumulates from those scoring actions. This differentiates the tool effectively.

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 provides specific use cases: 'due diligence, MiCA Article 72 ongoing monitoring reports, and detecting counterparties whose ESG posture is degrading.' This gives clear context for when to use the tool. It lacks explicit when-not-to-use guidance or mention of alternatives, but the implicit differentiation from point-in-time tools (esg.score) and the focus on historical trend is sufficient for an agent to make a reasonable choice.

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