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

Annotations declare the write/destructive/non-idempotent profile, and the description goes well beyond them by disclosing the cascade: 'Changes the cost of every recipe using the ingredient from that date.' It also explains the active-cost resolution rule (latest effective_at not after the date) and the one-cost-per-ingredient-per-date constraint, which is exactly the sensitivity an agent needs before mutating.

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-loaded with the operation class, then scope, then side effects, then the exclusion, then the endpoint. Five short clauses, no filler, and no sentence that could be deleted without losing signal.

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 destructive 6-parameter mutation with no output schema, the description covers scope, side effects, and the key restriction. What is missing is only the return value (whether the created cost id comes back) and error behavior on the subrecipe case.

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 would be 3, but the description adds real semantics: 'price and shipping are per quantity x unit' explains how three separate numeric fields combine, which the schema alone does not. The effective_at resolution rule likewise clarifies a parameter the schema only labels as a date.

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?

Specific verb+resource: 'add a price for an ingredient' keyed to effective_at, with the 'WRITE:' prefix making the operation class unmistakable. The effective-dating framing implicitly separates it from update_ingredient_cost, but no sibling is named outright, so an agent must infer the create-vs-update boundary.

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 a hard exclusion ('Not allowed for subrecipe ingredients') and explains that the cost applies from a date forward, which tells the agent when this tool is the right choice. It stops short of explicitly routing to recipal_update_ingredient_cost or recipal_list_ingredient_costs for existing/historical costs.

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