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

Annotations already cover read-only, idempotent, closed-world behavior, so the description's main added value is the null-field semantics ('a null field means the brand does not state it, not that the answer is no') and the explicit absence of prices. That is useful behavioral context beyond the annotations, though it does not discuss error handling for an unknown code.

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?

The purpose is front-loaded and the two caveat sentences are valuable. The middle field list is long and dense but each item describes a returned field, so it largely earns its place; a bulleted or more structured presentation would improve readability.

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 enumerating returned fields and explaining null values and missing price data. It stops short of describing error behavior for an invalid LC code or exactly what 'where it works' and 'elements in stock' contain, but it is substantially complete for this read-only lookup.

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%, so both the code formats and the language enum are already fully documented in the schema. The description adds little parameter-specific meaning beyond repeating that lookup is by LC code, so the baseline 3 is appropriate.

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 states a specific verb and resource ('Facts about one composition by its LC code') and enumerates the exact fields returned. It is clearly a single-item lookup, which distinguishes it from search_compositions even though the sibling is not named.

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?

Usage is implied by 'one composition by its LC code' and the required code parameter. However, the description never explicitly says when to use this instead of search_compositions or ask_brand, nor does it mention prerequisites such as obtaining a valid LC code first.

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