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

The annotations already declare this as a read-only, idempotent, closed-world lookup, so safety is covered. The description adds genuinely new behavioral context: data provenance (IPCC 2006, AR5/AR6), official Viet Nam grid values with the specific 2024 figure, and the regulatory citation — all of which tell the agent the data is authoritative and citable rather than a computed result.

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 tight sentences with the resource and its contents front-loaded, followed by the intended action (cite in the report). The parenthetical enumerations are dense but each item is informative; the only mildly expendable content is the very specific document citation string.

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?

With no output schema, the description reasonably characterizes the returned data by listing the factor fields and their standard references, and it tells the agent what to do with the result. It does not describe the response shape or organization by category, but for a static reference lookup the coverage is nearly 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 description coverage is 0% for the single enum parameter, so the description carries the burden. It enumerates the categories (fuels, refrigerants, grid) that map to the enum values, which is partial compensation, but it never explains what `kind` does, what `all` returns, or what happens when it is omitted (0 required parameters).

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 names a specific resource (built-in default emission factors) and enumerates its contents: fuels with NCV/CO2/CH4/N2O/density, refrigerant GWPs for AR5/AR6, and Viet Nam grid factors by year. It also establishes the relationship to calculate_ghg_inventory. It stops short of distinguishing itself from the sibling cbam_default_value, which is also a default-value lookup.

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?

"Built-in default factors used by calculate_ghg_inventory" and "Cite them in the report" imply the context of use: retrieve these when populating or documenting an inventory. However, there is no explicit when-to-use versus cbam_default_value or versus user-supplied factors, and no stated conditions or exclusions.

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