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

With no annotations, the description carries the full burden, and it does contribute real behavioral content: the statutory phase-in rates (40/70/100%) disclose that the result is year-dependent, which is genuine context beyond a restated name. However, it never states that this is a pure, side-effect-free calculation, nor what it returns (EUA quantity vs. monetary exposure), leaving key behavioral gaps.

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?

A single dense sentence that front-loads the verb and resource, then adds the phase-in schedule as supporting detail. No filler, no redundancy.

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 5-parameter calculation tool with no annotations and no output schema, the description grounds the regulation and the year rates but says nothing about the return value (EUA count, EUR cost, or both) or units/precision. It is usable but not fully self-sufficient.

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 only 20%, so the description would ideally explain the other four parameters; instead it only reinforces reporting_year (already documented in the schema). The enum values (VLSFO/HFO/MGO/LNG/B24/B30, INTRA_EU/EXTRA_EU) and field names are largely self-evident, and the phase-in rates add year semantics, which keeps this at an adequate baseline rather than worse.

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?

Names a specific verb ('Calculates') and a precise resource ('EU ETS Maritime allowance (EUA) surrender obligations'), anchored to Directive (EU) 2023/959. The ETS framing implicitly separates it from the FuelEU-prefixed siblings, but it never states that distinction explicitly, so an agent that only skims could still confuse it with calculate_fueleu_maritime_penalty.

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?

There is no when-to-use guidance, no exclusions, and no pointing to an alternative sibling. The regulatory scope and phase-in years hint at applicability, but the agent must infer the conditions under which this tool rather than the FuelEU penalty/banking tools is the right call.

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