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

With no annotations, the description carries the full burden for behavioral disclosure. It states the calculation goal and the shared weight_kg across legs, but does not mention output units (e.g., kg CO2e), error behavior, or any side effects. For a read-only calculation tool, the omission of return format is a moderate gap.

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?

Three sentences, front-loaded with the core purpose, followed by essential usage details and a single clarifying constraint. No wasted words, 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?

For a tool with 10 params and no output schema, the description covers the key selection and invocation aspects: modes, single vs multi-leg, location formats, and shared weight. It stops short of describing the return value or limitations, but given the schema's thorough parameter documentation, this is reasonably 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 coverage is 100%, so the baseline is 3. The description adds meaningful semantics beyond the schema: location types (UN/LOCODE, IATA, free-text, lat/lon) and the note that weight_kg is shared across legs. This helps the agent correctly construct multi-leg requests and understand location input flexibility.

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 begins with a specific verb + resource: 'Calculate CO2e emissions for freight transport' and enumerates supported modes (sea, road, rail, air). This clearly distinguishes it from sibling tools like calculate_emissions_flight (likely passenger air) and calculate_emissions_activity (generic activities).

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 clear usage context: it supports single-leg and multi-leg intermodal journeys, and explains when to use the legs[] array. It does not explicitly name alternative tools for exclusion, but the freight-specific scope and reference to 'multi-leg intermodal' effectively guide selection among the sibling set.

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