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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely new behavior: entries are historical, each carries effective date/quantity/unit/price/shipping, and the 'active' entry is defined by the latest effective_at not in the future — semantics an agent could not derive from the schema or annotations.

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 dense sentences with the resource and return shape front-loaded, and no filler. The trailing 'GET /ingredients/{id}/ingredient_costs' is redundant for an agent that already has the tool name and schema, which keeps it from a 5.

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?

There is no output schema, so the description carries the burden of describing return values — and it does, listing the per-entry fields and explaining how the active entry is determined. Combined with a fully documented input schema and read-only annotations, an agent has everything needed to call and interpret this 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 description coverage is 100%: page, per_page and ingredient_id are all documented in the schema itself, including the default and the next_page guidance. The description adds no parameter-level detail beyond that, so the baseline 3 applies.

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 resource and scope — the cost *history* of one ingredient — and enumerates what each entry contains (effective date, quantity, unit, price, shipping). The word 'history' plus the rule for identifying the active entry implicitly separates it from recipal_list_current_ingredient_costs and recipal_get_ingredient_cost, but no sibling is named outright.

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 parenthetical about the latest non-future effective_at entry implies this is the tool for full/dated cost history rather than just the current cost, which is a useful usage signal. However, it never says explicitly when to choose this over recipal_list_current_ingredient_costs or recipal_get_ingredient_cost, 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.