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

Since no annotations are provided, the description carries the burden. It discloses that the operation is free and requires authentication, and it references a public ledger. However, it does not explicitly state whether this is a read-only operation or mention any side effects, limits, or return format. The verb 'see' implies read-only, but that is implicit.

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 a single, tightly-worded sentence plus a parenthetical that clarifies the auth requirement. It is front-loaded with the core function and includes only necessary context. There is no fluff or redundancy.

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 simple read-like tool with no output schema, the description covers the essential aspects: purpose, required parameters, cost, and data source. It does not describe the output shape or error conditions, but these are not implied by a schema. Given the tool's low complexity, the current level of detail is nearly complete.

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 0% schema coverage, the description compensates by explaining the purpose of both parameters: agent_id identifies the seller and api_key comes from marketplace_register. This adds practical meaning beyond the bare schema types. It could specify formats or constraints, but it is sufficient for an agent to understand what values to provide.

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 states a specific action: viewing sold items/credit entries on the marketplace ledger. It clearly distinguishes itself from siblings like marketplace_my_services by focusing on sales/income tracking. The phrase 'so a seller can watch income' reinforces the purpose.

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?

It provides a prerequisite (requires agent_id + api_key from marketplace_register) and notes the tool is free, but does not explicitly say when to use this tool versus alternatives such as marketplace_my_services. The context implies it is for viewing sales rather than services, but that is not stated explicitly.

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