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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavior: field-level partial update ('Only the fields given are changed') and currency inheritance ('A new price stays in the gift's currency unless currency is given too'), both of which are not derivable 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?

Three short sentences, front-loaded with the verb and resource, followed by the partial-update rule and the one non-obvious semantic (currency). No redundant restatement of the title or schema.

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 6-parameter partial-update tool with no output schema and thin schema coverage, the description supplies the semantics an agent needs: which fields exist, the status vocabulary and the currency default. Minor gaps remain around the response (e.g., what the updated gift looks like) and per-field constraints such as the name length limit.

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?

With only 17% schema description coverage, the description has to carry the load, and it does: it names the four updatable fields, enumerates the status values (idea, bought, wrapped, done) and explains the price/currency interaction. It does not explain gift_id, but its role is obvious from the required field name.

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 definition opens with a specific verb and resource ('Changes a gift on the signed-in person's gift list') and enumerates the mutable fields (status, price, name, notes). It hints at scope by tying the resource to the signed-in person's list, which separates it from wishlist-item tools, but it never names the closest siblings (update_wishlist_item, update_gift_list) to make the boundary 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?

'Only the fields given are changed' usefully signals partial-update semantics, implying this is the tool for editing an existing gift rather than adding one. However, there is no explicit when-to-use or when-not framing, no mention of prerequisites such as owning the gift, and no routing to alternatives for list-level or wishlist-level edits.

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