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

Annotations already cover readOnly/non-destructive/closed-world, but the description adds real domain behavior beyond them: it discloses the conditional return shape (exact price and customer link for fixed-price goods vs. an enquiry link when a quote is required) and explicitly states "Never charges a customer." That branch information is not derivable from any structured field and materially affects how an agent presents the result.

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?

Three short sentences, front-loaded with the action and identifier, followed by the return behavior and the no-charge guarantee. No redundant wording and nothing buried.

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 helpfully summarize the two possible return shapes, which is the right instinct. However, for a tool with an undocumented language parameter and no stated behavior on a missing or non-public ID, the definition leaves gaps an agent would hit in practice.

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 0%, so the description carries the full burden, and it only partly discharges it: "canonical ID" gives meaning to the required id parameter, but the language parameter (fr/en enum) is never mentioned, so its purpose and default are undocumented anywhere. The pattern and maxLength constraints exist in the schema but their significance is unexplained.

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?

"Read a public offer by its canonical ID" states a specific verb (read/lookup) and resource (a single offer), and "exact" plus the singular framing distinguishes it from the plural siblings like acorn_find_offers and acorn_compare_offers. It stops short of naming any sibling, so the differentiation is implicit rather than explicit.

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?

"By its canonical ID" implies this is the follow-up call once an ID is known, which is useful context, but the description never states when to choose this over acorn_find_offers or acorn_compare_offers, nor what to do if the ID is unknown. Usage is inferable rather than stated.

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