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

Beyond the readOnlyHint=false annotation (which only signals mutation), the description discloses a wealth of behavioral detail: description changes trigger search re-indexing, price changes keep the old price on record, status affects visibility and sales, the upload-completion workflow reads the object and records size/type, and the reply carries _untrusted fields. This goes well beyond what annotations provide, giving the agent a precise model of side effects and output shape.

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?

Although long, the description is densely informative and well-structured: purpose and auth up front, then each field with its behavioral nuance, then the special upload flow, then deletion pointer and reply format. Every sentence adds necessary detail; there is no filler or repetition, and the structure guides the reader from core intent to edge cases.

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 complex tool with 13 parameters, special flows, and no output schema, the description is remarkably complete. It covers return value shape, ownership constraints, field-specific effects, the awaiting_upload handshake, idempotency, and even refusal rules for use_cases. An agent has everything needed to call this correctly in all scenarios.

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 schema coverage at only 46%, the description carries the bulk of the semantic load and does so thoroughly. It explains the format of use_cases (up to four {when, example} pairs, with length limits and a refusal rule), the meaning of status (paused hides and stops sales), the upload_complete + sha256 relationship, and idempotency_key behavior. Every parameter's purpose and edge cases are clarified beyond the raw schema.

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 opens with a clear verb-resource pair: 'Edit one of your listings', immediately distinguishing it from createListing (creation) and deleteListing (deletion). It explicitly names the resource and scope ('your listings'), and adds the ownership/API-key condition, so an agent can unambiguously identify what this tool does and when it applies.

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 gives explicit usage context: it states the API-key and ownership requirement, explains the special awaiting_upload flow (when to call with upload_complete), and points to deleteListing for deletion. It effectively says when to use this tool and when to use alternatives, leaving no ambiguity about selection.

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