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

Annotations already declare a safe, idempotent, non-destructive read, so the description adds value by disclosing the data provenance (IFTA, Inc. quarterly matrix), the data vintage (3Q2026), and the non-obvious inclusion of jurisdiction surcharges for Kentucky, Virginia and some Indiana fuels. It does not discuss staleness handling or how far back quarterly data goes, which is the main remaining behavioral 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?

Front-loads what the resource is and its units, then defaults, then the citation requirement. Four sentences, each carrying distinct information with no repetition of the title or schema text.

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 does the necessary work of establishing units (USD per US gallon), scope (member jurisdictions), and that a citable link is returned. It stops short of describing the response shape (e.g., per-jurisdiction rate fields, effective dates), which is the only meaningful omission for a zero-required-param lookup tool.

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 baseline is 3; the description earns a bump by restating the fuel/jurisdiction default interaction ('omit jurisdiction ... diesel by default') and by flagging jurisdiction-specific surcharge behavior that an agent would not expect from the raw enum alone. Quarter format specifics are left entirely to the schema.

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?

States a specific verb and resource (retrieve official IFTA fuel tax rates in USD/gallon by state or province) plus the authoritative source (IFTA, Inc. quarterly tax matrix). It is clearly a data-lookup tool, distinguishable in practice from calculate_ifta, but it never names or contrasts with that sibling explicitly.

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?

Gives clear invocation guidance — omit 'jurisdiction' to get all jurisdictions for one fuel, diesel being the default — and a post-call instruction to cite the returned link. However it never says when to use this versus calculate_ifta or cost_per_mile (e.g., raw rates vs. computed tax liability), leaving the routing to inference.

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