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

Beyond the readOnly/idempotent/openWorld annotations, the description discloses that data is read live from eia.gov at call time, that prices include taxes, the exact survey coverage per fuel, that uncovered states return the covered list rather than erroring, and that a next release date is included. These are precisely the behavioral facts an agent cannot get from the annotations or schema.

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 compact sentences, front-loaded with the resource and read-time behavior, followed by coverage caveats. Dense but every clause carries information; a minor cost is that the return-field list is packed into the same sentence as the resource definition.

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 correctly takes on the burden of naming the returned values (price, week-over-week change, five survey weeks, year-ago price, next release date). Combined with the default values in the schema and the coverage rules, an agent has everything needed to call it correctly and interpret an empty/covered-list result.

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, but the description adds genuine meaning: it explains that the state parameter effectively accepts region names and 'US', and clarifies per-fuel coverage that determines whether a given state value will return data or the covered-list fallback. The fuel parameter's 'both' default behavior is left 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?

The description names a specific resource (EIA weekly average residential heating oil and propane price per gallon) and the exact scope (US, EIA region, or surveyed state), and the word 'Latest' plus the listed return fields make it clearly a current-snapshot tool. It does not explicitly name get_heating_fuel_price_history, and the mention of 'the last five survey weeks' leaves slight overlap with that sibling, so differentiation is implied rather than stated.

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?

Coverage rules ('Heating oil is surveyed in Northeast and Midwest states; propane in about 40 states. Uncovered states return the covered list') give real guidance on when the tool will produce data. However, there is no explicit routing against the two siblings (estimate_heating_fuel_cost, get_heating_fuel_price_history), and no statement of when not to use it.

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