ebay_update_promotional_shipping_rule

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

Annotations already signal a non-read-only, idempotent write, so the bar is lower. The description adds useful context beyond them: the mutation returns 204 No Content (so no body to parse) and requires the sell.account scope, both of which matter for a write call.

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 action and mutable fields, followed by the header, return, and auth facts in compact form. Dense with no filler, though the parenthetical API reference is mildly redundant.

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 mutation with no output schema, the description covers what an agent needs: the mutable scope, required scope, marketplace header handling, and a verification path. Return behavior is addressed via the 204 note, leaving only granular field semantics to the (complete) schema.

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 the nested fields, enums, and the marketplaceId header are already fully documented structurally. The description restates the updatable fields at a high level without adding syntax or format detail beyond the schema, matching the baseline of 3.

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 verb (Update) and resource (existing promotional combined-shipping rule) and enumerates the mutable fields (thresholds, item count, shipping cost, combinedDuration). 'Existing' implicitly separates it from ebay_create_promotional_shipping_rule, though it never names that sibling.

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 clear context: update (not create) an existing rule, requires the sell.account scope, and directs the agent to ebay_get_combined_shipping_rules to confirm the result. No explicit when-not-to-use note or named alternative for other rule types, but the operating context is well specified.

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