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

Annotations (readOnlyHint=false, destructiveHint=false) are consistent, but the description adds rich context: edit quota and re-review for certain fields, auto-sync behavior, price change implications. This far exceeds what annotations alone convey.

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 description is efficiently structured: primary action first, then side effects, then special cases, then exclusions. Every sentence earns its place with concrete information, no fluff.

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?

Given 9 parameters, nested objects, and no output schema, the description covers key behaviors (quota, review, sync) and edge cases. It lacks details about the return value or field constraints (e.g., max length), but it is comprehensive for a complex tool.

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?

The description adds value by advising to 'pass only the fields to change' and by highlighting that editing images/title/description has specific consequences. While schema coverage is 56%, the description does not detail every nested parameter, but the guidance is clear enough for effective use.

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 clearly states 'Update one of the authenticated agent's listings' with a specific verb and resource. It distinguishes from sibling tools like create_listing and close_listing by focusing on updates and explicitly referencing close_listing for publish state changes.

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?

The description provides explicit when-to-use guidance ('Pass only the fields to change'), notes quotas and review triggers, and explains special behavior for synced listings. It also tells when not to use (changing publish state of synced listings) and points to the alternative tool (close_listing).

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